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1
Finamore, S. M., H. L. Gibson, and P. C. Thurston. "Archean Synvolcanic Intrusions and Volcanogenic Massive Sulfide at the Genex Mine, Kamiskotia Area, Timmins, Ontario." Economic Geology 103, no. 6 (September 1, 2008): 1203–18. http://dx.doi.org/10.2113/gsecongeo.103.6.1203.
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Tucker Barrie, C., M. P. Gorton, A. J. Naldrett, and T. R. Hart. "Geochemical constraints on the petrogenesis of the Kamiskotia gabbroic complex and related basalts, Western Abitibi Subprovince, Ontario, Canada." Precambrian Research 50, no. 3-4 (May 1991): 173–99. http://dx.doi.org/10.1016/0301-9268(91)90020-b.
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Tucker Barrie, C., and Don W. Davis. "Timing of magmatism and deformation in the Kamiskotia-Kidd Creek area, Western Abitibi subprovince, Canada." Precambrian Research 46, no. 3 (February 1990): 217–40. http://dx.doi.org/10.1016/0301-9268(90)90003-9.
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McDougall, Raymond. "Mineral Highlights from the Bancroft Area, Ontario, Canada." Rocks & Minerals 94, no. 5 (August 5, 2019): 408–19. http://dx.doi.org/10.1080/00357529.2019.1619134.
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Kile, Daniel E. "Mineralogy of the Amethyst Mines in the Thunder Bay Area, Thunder Bay, Ontario, Canada." Rocks & Minerals 94, no. 4 (June 11, 2019): 306–43. http://dx.doi.org/10.1080/00357529.2019.1595939.
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Fralick, Philip W., and Andrew D. Miall. "Sedimentology of the lower huronian supergroup (early proterozoic), Elliot lake area, Ontario, Canada." Sedimentary Geology 63, no. 1-2 (June 1989): 127–53. http://dx.doi.org/10.1016/0037-0738(89)90075-4.
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Sharpe, David R., and Peter J. Barnett. "Significance of Sedimentological Studies on the Wisconsinan Stratigraphy of Southern Ontario." Géographie physique et Quaternaire 39, no. 3 (December 4, 2007): 255–73. http://dx.doi.org/10.7202/032607ar.
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ABSTRACTDetailed facies mapping along Lake Erie and Lake Ontario Bluffs, plus other studies illustrate that sedimentological studies, especially those with geomorphic or landform control, have had three main effects on the Wisconsinan stratigraphy of Ontario: (1) improved understanding of depositional processes and environments of several major rock stratigraphic units, without altering the stratigraphic framework, (2) aided correlation of drift sequences, and (3) questioned previous interpretations and stratigraphic correlations of drift sequences. Thus sedimentological analysis can not be separated from stratigraphy because the interpretation of depositional environnments of many mapped strata relies on their geometry and the inclusion of regional data. The geomorphic control provided by sedimentological study of surface landforms is also important because assessment of older buried sediments such as those at the Scarborough Bluffs has been hampered by the failure to determine landform control. The Late Wisconsinan stratigraphy of Southern Ontario generally remains unchanged, except for questions on the role of climate versus ice margin dynamics. The pre-Late Wisconsinan stratigraphy is scarce and not well defined, yet sedimentary studies support the presence of glacial ice in the Ontario Lake basin for all of the Middle Wisconsinan and possibly earlier, including the formation of the Scarborough delta. Large channel cut and fill sequences in the Toronto area (Pottery Road Formation), initially interpreted as resulting from subaerial erosion, were probably formed by subaqueous or subglacial meltwater erosion. If so, the pre-Late Wisconsinan stratigraphy in southern Ontario changes because the Pottery Road Formation may not be an Early Wisconsinan correlative of the St. Pierre beds. The channel example illustrates that stratigraphie correlation without sedimentological investigations may be misleading.
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Motazedian, Dariush, and James Hunter. "Development of an NEHRP map for the Orleans suburb of Ottawa, Ontario." Canadian Geotechnical Journal 45, no. 8 (August 2008): 1180–88. http://dx.doi.org/10.1139/t08-051.
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The average shear-wave velocity to a depth of 30 m (Vs30) has been obtained for 73 sites in the Orleans area in the northeast part of the City of Ottawa. Measurements of Vs30 were made using both ground surface reflection and refraction methods. In addition, borehole data was used to estimate Vs versus depth profiles using average Vs values assigned to distinct geological units. High values of Vs (>1500 m/s) were obtained in areas of thin surficial sediments overlying Paleozoic bedrock, and low Vs values (<180 m/s) were calculated in areas of thick late–post-glacial clay. The Vs30 values have been used to prepare an NEHRP map for the study area. Much of the suburb of Orleans is classified as NEHRP zone E, whereas the perimeter areas and some isolated central areas are classified as zones ranging from zone D to zone A. The presence of thick unconsolidated late–post-glacial sediments deposited in the Champlain Sea is the main contributing factor to the wide range of average shear-wave velocities in the study area.
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Mohajer, Arsalan A. "Seismicity and Seismotectonics of the Western Lake Ontario Region." Géographie physique et Quaternaire 47, no. 3 (November 23, 2007): 353–62. http://dx.doi.org/10.7202/032963ar.
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ABSTRACTThe western Lake Ontario region, a traditionally perceived area of low seismic risk, is densely populated and is home to, among other critical facilities, the nuclear reactors of Pickering and Darlington. These and other characteristics of the region call for improved estimates of seismic hazard. Due to a lack of understanding of the causative geological sources and recurrence characteristics of the reported seismic activity, there is considerable uncertainty regarding estimated ground motion parameters, a fundamental component of seismic hazard assessments. To attempt to improve the definition of the seismic source zones and, consequently, seismic hazard assessments, the hypocentres of about 30 local earthquakes were recomputed. A new data compilation, based on the revised locations or those with the least travel-time residuals, shows that local microearthquakes (ML"3.5) generally occur along, or at the intersection of, prominent aeromagnetic or gravity anomalies. A notable seismicity trend extends in a northeast-southwest direction between Toronto and Hamilton, and is bounded by magnetic lineaments. A major geological structure, the Central Metasedimentary Belt Boundary Zone (CMBBZ), coincides with a strong aeromagnetic anomaly which extends to the northeast into the Western Québec Seismic Zone. This magnetic lineament also extends to the south, across Lake Ontario, to join the Akron (Ohio) magnetic boundary that was associated with several historical earthquakes and with a mb=4.9 earthquake in 1986. Most of the seismic events recorded instrumentally in the 20th century have occurred within a depth range of 5 to 20 km. This observation supports the correlation of local earthquakes with deep geophysical and geological features, suggesting contemporary reactivation of basement structures. This may imply that a more conservative deterministic hazard estimate is needed to verify the probabilistic approach currently used to assess seismic hazard in southern Ontario.
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Cooper, A. J. "Waste disposal site selection techniques in Quaternary terraine Ontario, Canada." Geological Society, London, Engineering Geology Special Publications 7, no. 1 (1991): 211–17. http://dx.doi.org/10.1144/gsl.eng.1991.007.01.19.
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AbstractThick and predictable deposits of fine grained Quaternary materials have been used for the siting of waste management facilities in Ontario. The search for such sites is founded on the application of techniques in Quaternary geology and hydrogeology. Two examples are presented. Oxford County is located southwest of Toronto in an area of parallel morainic ridges separated by flat till plains. Conventional wisdom would focus on the till plains for thick, consistent fine grained Quaternary Sediments. However, the careful analysis of the Quaternary stratigraphy and glacial history revealed that better sites are located along the moraines. A site on the Ingersoll Moraine was studied in detail and defended at a public hearing. Concerns about the geology of the materials were allayed by the confirmation of homogeneous clayey silt materials exposed when the site opened in late 1986. A much wider ranging search was undertaken for a major hazardous and liquid industrial waste treatment and disposal facility for the Province of Ontario. Progressively more detailed investigations of the Quaternary geology were used to assist a multi-disciplinary site selection team. Initial interpretations covered an area of 75 000 km2 at a scale of 1:250 000. Eight candidate sites were then selected for further investigation with five continuously sampled stratigraphic boreholes. The chosen site is located in a depression in the bedrock filled with 40 m of glaciolacustrine clayey silt. Site specific hydrogeological and geotechnical studies were integrated with a detailed geological investigation.
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MIALL, ANDREW D. "Sedimentation on an early Proterozoic continental margin under glacial influence: the Gowganda Formation (Huronian), Elliot Lake area, Ontario, Canada." Sedimentology 32, no. 6 (December 1985): 763–88. http://dx.doi.org/10.1111/j.1365-3091.1985.tb00733.x.
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Eyles, N., and K. W. F. Howard. "A hydrochemical study of urban landslides caused by heavy rain: Scarborough Bluffs, Ontario, Canada." Canadian Geotechnical Journal 25, no. 3 (August 1, 1988): 455–66. http://dx.doi.org/10.1139/t88-051.
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Scarborough Bluffs is a 15 km long stretch of the Lake Ontario shoreline east of downtown Toronto. This heavily urbanized area currently represents Canada's most serious erosion problem. The worst affected zone is 1.5 km long and lies along South Marine Drive where 50 m high bluffs are failing by shallow retrogressive failures of jointed glacial clays over underlying deltaic sands and clays. The erosion rate is about four times that for the coastline as a whole.Heavy rains in the Toronto area in August and September 1986 produced a spate of slope failures and mud flows. Particularly heavy storms on September 10 and 29 triggered extensive retrogressive slope failures at South Marine Drive. Hydrochemical investigations of discharge waters suggest that slope failure was caused by surface runoff on the bluff top recharging lower slope areas by infiltration through joints in the upper clay capping. Discharge of water from the lower slope is impeded by less permeable barriers in the deltaic stratigraphy at the site and by a cover of clayey slope debris. Data suggest that provision for adequate drainage of the bluff top, by interceptor drains, is a prerequisite for controlling slope behaviour in the area. Key words: slopes, erosion, groundwater, hydrochemical, recharge, drainage.
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Fee, E. J., and R. E. Hecky. "Introduction to the Northwest Ontario Lake Size Series (NOLSS)." Canadian Journal of Fisheries and Aquatic Sciences 49, no. 12 (December 1, 1992): 2434–44. http://dx.doi.org/10.1139/f92-269.
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The rationale, design, and limitations of the Northwest Ontario Lake Size Series (NOLSS) research program are described. The primary purpose of NOLSS is to discover how lake size per se influences limnological and fisheries phenomena, so that conclusions drawn from studies of particular lakes can be rigorously scaled and applied to lakes of other sizes. NOLSS consists of six lakes located in a remote wilderness region of Northwest Ontario. These lakes were chosen for their geological, hydrological, and morphological similarity (Canadian Shield geology; water renewal time> 5 yr; fully stratified in summer), but they form an exponential gradient in surface area (from 89 to 34 700 ha.) Associated with this gradient of lake size are gradients of physical properties (turbulent energy, mixing depth, thermal behaviour) to which biological communities must adapt. NOLSS fills the conspicuous gap in size that separates two well-studied groups of lakes in Northwest Ontario: the Experimental Lakes Area (ELA), where whole-lake manipulation experiments are performed, and the Laurentian Great Lakes (Nipigon, Superior), where these experiments find some of their most important applications.
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DICKIN, A. P., and R. H. MCNUTT. "An application of Nd isotope mapping in structural geology: delineating an allochthonous Grenvillian terrane at North Bay, Ontario." Geological Magazine 140, no. 5 (September 2003): 539–48. http://dx.doi.org/10.1017/s0016756803008070.
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Fifty new Nd isotope analyses are presented from the North Bay area of the Grenville Province in Ontario. These data are used to map the extent of an allochthonous Grenvillian terrane which is an outlier of the Allochthonous Polycyclic Belt of the Grenville Province. Amphibolite facies orthogneisses from the allochthonous terrane have depleted mantle Nd model ages (TDM) below 1.8 Ga, whereas the gneisses of the structurally underlying parautochthon almost invariably have model ages above 1.8 Ga. The distribution of model ages is consistent with the distribution of distinct types of metabasic rock, used by other researchers as the criterion for recognizing rocks of the allochthonous and parautochthonous belts of the Grenville Province. The agreement between these different types of evidence demonstrates that Nd isotope mapping is a reliable and powerful tool for mapping terrane boundaries in high-grade metamorphic belts.
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Hicock, Stephen R. "Calcareous Till Facies North of Lake Superior, Ontario: Implications for Laurentide Ice Streaming." Géographie physique et Quaternaire 42, no. 2 (December 18, 2007): 120–35. http://dx.doi.org/10.7202/032719ar.
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ABSTRACTIn the Geraldton and Hemlo areas distantly-derived carbonate tills lie between slightly to non-calcareous tills and can be distinguished by textural, carbonate, and clast compositions. Their occurrence and uniform character over large areas of the Shield attest to high sediment flux by rapid movement of distal debris within the southern part of the Laurentide Ice Sheet. This is consistent with low surface profiles reconstructed for the Superior and Michigan lobes which were likely fed by ice north of Superior and probably affected by ice streaming. Till deposition in the Geraldton and Hemlo areas can be explained with one southwestward glacial advance. A broad ice stream probably issued out of James Bay and up the Albany conduit between zones of normal ice velocity within the Laurentide marginal area. It may have split to flow down the Drowning and Kenogami troughs. Eventually, zones of ice streaming reached the Geraldton and Hemlo areas where Shield uplands induced lee side extending flow, downward transport, and lodgment of calcareous englacial debris on local tills. Following the glacial maximum much of the distal englacial debris was laid down by subglacial meltout. However, a glacial reactivation occurred which moulded drumlins in the carbonate tills near Geraldton and deposited an upper calcareous lodgment till at Hemlo. Final Laurentide decay resulted in meltout of supraglacial debris that had been sheared up to or near the glacier surface from the stoss sides of the uplands.
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Hugenholtz, Chris H., and Denis Lacelle. "Geomorphic Controls on Landslide Activity in Champlain Sea Clays along Green’s Creek, Eastern Ontario, Canada." Géographie physique et Quaternaire 58, no. 1 (June 26, 2006): 9–23. http://dx.doi.org/10.7202/013108ar.
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AbstractLandslides in Champlain Sea clays have played an important role in shaping Eastern Ontario’s landscape. Despite extensive research, there is a limited understanding of the relations between landslide activity, climatic controls, and the geomorphic evolution of river valleys in Champlain Sea clay deposits. With these issues in mind, a study was undertaken to determine the controls on the spatio-temporal distribution of contemporary landslide activity in valley slopes composed of Champlain Sea clay. The study area was the Green’s Creek valley located in the east end of Ottawa, Ontario. Observations and measurements indicate that landslide activity is closely related to valley development. An inventory of landslide activity from 73 years of aerial photographs revealed that landslides occurred preferentially in slopes located on the outside of meander bends, and that they often recurred in the same slope after a period of ripening. The largest and highest density of landslides occurred along a major tributary valley where geomorphic features such as knickpoints, V-shaped valley profiles and bedrock depth-to-slope height ratios reflect an unstable phase of valley development. A small number of landslides incurred successive failures along the slopes of the backscarp for several years-to-decades after the initial failure. Correlation analysis showed that the temporal distribution of landslide activity has fluctuated in response to decadal-scale changes in the amount of precipitation.
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CONIGLIO, M., and A. E. WILLIAMS-JONES. "Diagenesis of Ordovician carbonates from the north-east Michigan Basin, Manitoulin Island area, Ontario: evidence from petrography, stable isotopes and fluid inclusions." Sedimentology 39, no. 5 (October 1992): 813–36. http://dx.doi.org/10.1111/j.1365-3091.1992.tb02155.x.
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Husain, Muin M., John A. Cherry, Scott Fidler, and Shaun K. Frape. "On the long-term hydraulic gradient in the thick clayey aquitard in the Sarnia region, Ontario." Canadian Geotechnical Journal 35, no. 6 (December 1, 1998): 986–1003. http://dx.doi.org/10.1139/t98-057.
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Much of the southwestern part of Ontario between Lake Huron and Lake Erie has a thin freshwater aquifer overlain by an aquitard of Late Pleistocene clayey glaciolacustrine deposits and underlain by a thick Devonian shale aquitard. In a large area east of the St. Clair River, where the Quaternary aquitard is 30-50 m thick, groundwater of Pleistocene origin (identified by 18O and 2H signature) occurs in the aquifer and in the bottom part of the Quaternary aquitard. Numerous piezometer nests in the aquitard show a downward hydraulic gradient with depth. In some areas, the aquitard has downward gradients only in the upper part and upward gradient in the lower part, indicating a transient condition. The piezometer nests in the clayey aquitard also show an increase in Cl- concentration with depth. Long-term piezometer monitoring at two sites show a major shift in the aquitard hydraulic gradient since 1983 and a large rise in head in the underlying aquifer. Analyses of initial aquifer water levels, reported in well drilling records, indicate a large decline in the potentiometric surface of the aquifer between the 1940's and the 1970's followed by a recent rise in the surface in part of the region. This pattern is consistent with well drilling and water use records indicating that 7000 wells were installed in the aquifer in the three decades since 1940 and that groundwater use has greatly diminished in the past 10-15 years due to rural pipeline distribution of lake and river water. The hydraulic gradient in the aquitard is slowly adjusting to the rise in the aquifer potentiometric surface. One-dimensional solute transport modelling provides close matches to the vertical profiles of Cl- migrating upward from the aquifer since deglaciation, 15 000 - 18 000 years before present, by diffusion with little or no advection. The lack of advection indicates a near-neutral long-term hydraulic gradient. As the withdrawal rate of water from the aquifer continues to decline, it is expected that the hydraulic head in the aquitard in much of the area westward of the recharge area will continue to adjust for many decades.Key words: clay, aquitard, aquifer, water use, hydraulic gradient.
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Morris, T. F., and R. I. Kelly. "Origin and physical and chemical characteristics of glacial overburden in Essex and Kent counties, southwestern Ontario." Canadian Journal of Earth Sciences 34, no. 3 (March 1, 1997): 233–46. http://dx.doi.org/10.1139/e17-022.
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The overburden of Essex and Kent counties, southwestern Ontario, has been described as consisting of a clayey silt to silty clay till overlying a gravelly unit resting on bedrock. Recent Quaternary geology mapping has identified additional materials and redefined the origin of others by determining the stratigraphic position and physical and geochemical properties of materials encountered in a sonic drilling program and field mapping. Catfish Creek Till was deposited on the bedrock surface during the Nissouri Stadial as ice advanced south over the area. As ice retreated during the Erie Interstade, fine-grained glaciolacustrine material was deposited in glacial Lake Leverett and overlay Catfish Creek Till. Tavistock Till was deposited over glacial Lake Leverett material as the Huron lobe readvanced south during the Port Bruce Stadial. As the Huron lobe retreated north, coarse-grained glaciolacustrine materials were deposited in the Leamington area. Ice from the Erie lobe deposited the Port Stanley Till along the north shore of Lake Erie in Kent County and deflected meltwater southward from the Huron lobe in the Blenheim area. A series of recessional moraines were deposited by the Huron lobe as it retreated north. The area is capped by a fine-grained glaciolacustrine deposit.
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Simms, Paul H., and Ernest K. Yanful. "Some insights into the performance of an experimental soil cover near London, Ontario." Canadian Geotechnical Journal 36, no. 5 (November 23, 1999): 846–60. http://dx.doi.org/10.1139/t99-046.
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An experimental soil cover constructed near London, Ontario, 23.2 m × 15.2 m in plan area, has been monitored for 2 years for percolation and water-content data. The cover was a multilayer system consisting of a compacted till barrier soil placed between evaporation and drainage barriers of sandy gravel. Half of the cover was capped with coarse stone to prevent erosion and the other half was covered with topsoil to facilitate revegetation. High percolation rates and substantial desiccation of the barrier soil were reported under the topsoil protection layer. Unsaturated-saturated liquid and vapour flow modelling shows that the topsoil may act as a capillary barrier to infiltration, thereby promoting desiccation of the underlying compacted till. Percolation through the cover was measured using lysimeters filled with 5-16 cm (2-6 in.) diameter stone placed directly underneath the compacted till. Though the field lysimeters report water and laboratory tests show no evidence of flow partitioning between coarse stone and gravel, two-dimensional unsaturated-saturated liquid flow modelling of the lysimeter-cover interaction predicts that the lysimeters should not report significant water. Phenomena not simulated by the modelling, which include macrostructure flow in the barrier soil, trickle flow in the coarse stone, and vapour diffusion, are investigated and discussed. Consideration of vapour flow yields results that are inconsistent with the predictions of the liquid flow modelling. Key words: capillary barrier, lysimeters, soil covers, unsaturated flow, vapour flow.
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D'Astous, A. Y., W. W. Ruland, J. R. G. Bruce, J. A. Cherry, and R. W. Gillham. "Fracture effects in the shallow groundwater zone in weathered Sarnia-area clay." Canadian Geotechnical Journal 26, no. 1 (February 1, 1989): 43–56. http://dx.doi.org/10.1139/t89-005.
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The Sarnia area of southwestern Ontario is underlain by thick deposits of clay-rich glacial till. From ground surface to between 4 and 6 m depth the clay till is fractured, oxidized, and penetrated by root holes. The water table fluctuates seasonally between the ground surface and the bottom of the weathered zone. Water-level response tests in conventional piezometers installed in augered holes in the weathered zone typically provide very low values of hydraulic conductivity (10−7–10−9 cm/s), which are similar to values obtained from the deeper unweathered and unfractured till. The augering process creates a smeared clay zone along the borehole walls that significantly reduces measured hydraulic conductivity values. In this study, the weathered-zone hydraulic conductivity was measured using unconventional piezometers, a large-diameter well, and a tracer experiment between two test pits. The smeared zone was removed or reduced around these installations, and the measured weathered-zone hydraulic conductivity was 10−5–10−7 cm/s, much higher than in the deep unweathered clay. These results, together with depth profiles of groundwater tritium and monitored water-level fluctuations, indicate that the weathered zone has hydraulic conductivity governed by fractures and has significant hydrologic activity in the fractures. Key words: clay, fractures, hydraulic conductivity, permeability, piezometer, tritium, tracer experiment, weathered zone.
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Beavon, Roy V. "Archean neptunian fissures and early history of the Destor-Porcupine fault zone, Timmins, Ontario, Canada." Canadian Journal of Earth Sciences 35, no. 12 (December 1, 1998): 1402–7. http://dx.doi.org/10.1139/e98-073.
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Neptunian dikes and fissures are intimately associated with a minor Archean sedimentary basin near Timmins, Ontario, in the southwestern part of Abitibi Subprovince of the Canadian Shield. These structures are associated with the late Archean Timiskaming unconformity, and were formed by clastic sedimentation in fissures opened by the reactivation and dilation of basement faults along a major crustal shear. A "pull-apart" origin is indicated for the sedimentary basin by published township maps and the underground geology of the Dome gold mine. The neptunian dikes and fissures are discussed in relation to previous stratigraphic and tectonic interpretations of the Timmins area.
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SHARMA, SAJAL, GEORGE R. DIX, and MIKE VILLENEUVE. "Petrology and potential tectonic significance of a K-bentonite in a Taconian shale basin (eastern Ontario, Canada), northern Appalachians." Geological Magazine 142, no. 2 (March 2005): 145–58. http://dx.doi.org/10.1017/s001675680400041x.
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A 6 cm thick K-bentonite, herein defined as the Russell Bed, occurs in an Upper Ordovician deep-basin shale succession in eastern Ontario, Canada, forming part of the distal Taconic foreland in eastern North America. The bed lies within the pygmaeus graptolite Biozone, which is about 451 to 452 Ma in age. Although some bentonites are reported from this interval in eastern North America, we are reporting the first set of compositional data for a bentonite of this age. Gamma-log correlation identifies a potential minimum distribution area of <2×105 km2 for the K-bentonite, covering part of southern Quebec, New York State and eastern Ontario. The deposit coincides with the first influx of distal turbdites into this shale basin, associated with Taconic flysch, and simultaneous abrupt ventilation of the once anoxic deep-water basin, which had formed initially after foundering of the Upper Ordovician carbonate platform. Concurrent intrabasinal extinction of several graptolite species suggests that change in sedimentation, palaeoceanography and volcanism were linked to a regional external process. Compositionally, the bentonite is distinct from the older Ordovician platform deposits in eastern North America. The deposit contains abundant titaniferous phlogopite with 1.6% BaO, fluoroapatite with 2.5% F, and dynamically shaped glass spherules now altered to clay. The spherules and clay matrix constitute 45% of the bed and, compositionally, define an illite (>90%)–smectite (I/S) structure with about 7.5% K2O%. Age-dating by Ar–Ar analysis of the phlogopite crystals yielded a younger than expected (440–445 Ma) age. This difference, along with evidence of localized chloritization of phlogopite, likely reflects known post-Ordovician hydrothermal activity within the basin. On the basis of several geochemical proxies, the magmatic source of the Russell K-bentonite falls within the trachyandesite field and was Ba-enriched. Comparison of geochemistry and mineralogy with older, Middle to Late Ordovician and younger Early Silurian K-bentonites within the Taconic orogen along eastern Laurentia and Baltica reveals that the potential source magma for the Russell Bed was more mafic, more alkaline, and less fractionated than sources typical of older (platform) bentonites. Instead, it is more similar to the younger Llandovery bentonites of Scandinavia and Scotland. It remains uncertain if it signals local or regional compositional change in volcanic source in the northern Appalachians.
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Carlson, Anders E., Peter U. Clark, and Steven W. Hostetler. "Comment: Radiocarbon deglaciation chronology of the Thunder Bay, Ontario area and implications for ice sheet retreat patterns." Quaternary Science Reviews 28, no. 23-24 (November 2009): 2546–47. http://dx.doi.org/10.1016/j.quascirev.2009.05.005.
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Rowe, R. K., R. W. I. Brachman, M. S. Hosney, W. A. Take, and D. N. Arnepalli. "Insight into hydraulic conductivity testing of geosynthetic clay liners (GCLs) exhumed after 5 and 7 years in a cover." Canadian Geotechnical Journal 54, no. 8 (August 2017): 1118–38. http://dx.doi.org/10.1139/cgj-2016-0473.
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Four geosynthetic clay liners (GCLs) serving as single liners were exhumed from below 0.7 m of silty sand on a 3:1 (horizontal:vertical) north-facing slope at the QUELTS site in Godfrey, Ontario, after 5 and 7 years. The 300 mm GCL overlaps with 0.4 kg/m supplemental bentonite were all physically intact. The exchangeable bound sodium was completely replaced with divalent cations. The GCL with the smallest needle-punched bundle size (average of 0.7 mm) and percentage area covered by bundles (4%) maintained low hydraulic conductivity (k) when tested under 0.07–1.2 m head with 10 mmol/L CaCl2 solution as the permeant. For GCLs with larger bundles (1.1–1.6 mm) and higher percentage area covered by bundles (9%–14%), k was low when the head was low (0.07 m). Once the applied head increased, k increased by 1–4 orders of magnitude depending on the (i) hydraulic gradient, (ii) size and number of the needle-punched bundles, and (iii) structure and mass of the bentonite per unit area. The results suggest that the GCLs can perform effectively as a single hydraulic barrier in covers providing that the head above the GCL is kept low (e.g., by a suitable drainage layer above the GCL).
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Sharpe, D. R., A. Pugin, S. E. Pullan, and G. Gorrell. "Application of seismic stratigraphy and sedimentology to regional hydrogeological investigations: an example from Oak Ridges Moraine, southern Ontario, Canada." Canadian Geotechnical Journal 40, no. 4 (August 1, 2003): 711–30. http://dx.doi.org/10.1139/t03-020.
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Hydrogeological models need to be supported by a clear understanding of the subsurface geology to provide effective assessment, flow modelling, or management of groundwater regimes. This paper illustrates how geophysical and sedimentological data can be used to significantly improve watershed-scale hydrostratigraphic models by advancing our understanding of the subsurface through regional hydrogeological investigations in the Greater Toronto Area. The example of a 3 km shallow seismic reflection survey that traverses a buried channel within Bowmanville Creek watershed, Oak Ridges Moraine, Ontario, illustrates a basis for linking geophysical and sedimentological properties to regional hydrostratigraphic parameters. Seismic reflection methods plus seismic stratigraphy and a well-constrained three-dimensional geological framework have helped to (i) identify regional hydrostratigraphic units, (ii) define properties and trends of these unitsfacies, (iii) improve depositional models that assist hydrogeological analysis, and (iv) establish a hydrostratigraphic framework within a watershed. The extent, proportions, boundaries, and variation in internal properties of major hydrostratigraphic units could be identified to greater than 100 m depth. Geostatistical analysis of seismic amplitudes was used to provide a quantitative measure of heterogeneity in a glaciofluvial aquifer with inadequate parameter support. Benefits to engineering practice include improved siting of monitors and tests from portrayal of the spatial organization, geometry, and variability of hydrostratigraphic units based on sedimentary architecture and environments of deposition. Hydrogeological modelling can be improved with better knowledge of the geometry of aquifers and aquitards and grid-cell boundaries that correspond with the defined sediment boundaries that control properties.Key words: Oak Ridges Moraine, hydrogeology, seismic stratigraphy, southern Ontario, sedimentology.
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Morris, T. F., D. Crabtree, R. P. Sage, and S. A. Averill. "Types, abundances and distribution of kimberlite indicator minerals in alluvial sediments, Wawa–Kinniwabi Lake area, Northeastern Ontario: implications for the presence of diamond-bearing kimberlite." Journal of Geochemical Exploration 63, no. 3 (October 1998): 217–35. http://dx.doi.org/10.1016/s0375-6742(98)00062-4.
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Evans, S. G., and G. R. Brooks. "An earthflow in sensitive Champlain Sea sediments at Lemieux, Ontario, June 20, 1993, and its impact on the South Nation River." Canadian Geotechnical Journal 31, no. 3 (June 1, 1994): 384–94. http://dx.doi.org/10.1139/t94-046.
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A large (est. volume 2.8 × 106 m3) landslide occurred in sensitive Leda clay on the east bank of the South Nation River at Lemieux, Ontario (45.4°N, 75.06°W), on June 20, 1993. The earthflow involved an area of about 17 ha and retrogressed a total of 680 m, 555 m into the flat plain above the river. No lives were lost but a motorist was injured when he drove into the landslide crater. The 1993 landslide occurred 4.5 km downstream of the well-known 1971 South Nation River landslide along a stretch of river that had experienced other historical landslides in 1895 and 1910. A band of earlier, undated, retrogressive sliding, between 100–130 m in width, was present at the base of the slope that failed in 1993, and the earthflow was probably triggered by a reactivation of these failures. Borehole information obtained in 1986 and 1987 in the vicinity of the landslide indicates that a zone of soft, sensitive marine clay existed beneath the flat farmland, which was overlain by a stiffer cap consisting of laminated marine-estuarine sands and deltaic silts and sands. The morphology of the debris suggests a mechanism that involves the fluidization of much of the landslide mass and subsidence, translation, and rotation of cap blocks. The stability number for the site was approximately 9.6, suggesting that the flow could have occurred as a result of extrusion of the soft sensitive clay layer due to undrained cap loading. Landslide debris temporarily blocked the South Nation River, causing flooding upstream and adversely affecting water quality downstream. Key words : landslide, earthflow, sensitive clay, debris hazards, water quality.
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Harris, Steven M., Neil R. Thomson, and Kentner S. Novakowski. "Determining the orientation of fracture planes in a weathered clay till using core samples." Canadian Geotechnical Journal 35, no. 2 (April 1, 1998): 386–94. http://dx.doi.org/10.1139/t98-008.
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A method has been developed to determine fracture plane orientations in clay-rich glacial deposits from core samples obtained from inclined borings. In this method, a portion of each core sample is removed to expose vertical and horizontal surfaces which are used to map each identified fracture plane. An analytical geometry technique is used in conjunction with the mapping data to determine the pole to each fracture plane. These fracture pole data can then be presented on a lower hemisphere equal area projection diagram to indicate preferential fracture plane orientations. The utility of the developed method is demonstrated through a detailed analysis of core samples collected from a 10 m x 10 m site located near Sarnia, Ontario. The data from this investigation indicated the presence of three sets of fracture planes; however, only one of these fracture sets was determined to be statistically significant. The developed method offers an alternative to mapping fracture plane orientations on exposed surfaces of trench excavations.Key words: clay, fractures, orientation, core samples.
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Gad, M. A., and I. K. Tsanis. "A GIS methodology for the analysis of weather radar precipitation data." Journal of Hydroinformatics 5, no. 2 (March 1, 2003): 113–26. http://dx.doi.org/10.2166/hydro.2003.0009.
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A GIS multi-component module was developed within the ArcView GIS environment for processing and analysing weather radar precipitation data. The module is capable of: (a) reading geo-reference radar data and comparing it with rain-gauge network data, (b) estimating the kinematics of rainfall patterns, such as the storm speed and direction, and (c) accumulating radar-derived rainfall depths. By bringing the spatial capabilities of GIS to bear this module can accurately locate rainfall on the ground and can overlay the animated storm on different geographical features of the study area, making the exploration of the storm's kinematic characteristics obtained from radar data relatively simple. A case study in the City of Hamilton in Ontario, Canada is used to demonstrate the functionality of the module. Radar comparison with rain gauge data revealed an underestimation of the classical Marshal & Palmer Z–R relation to rainfall rate.
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Ali, Mosaad, Shulin Sun, Wei Qian, Abdou Dodo Bohari, Dusabemariya Claire, Ajibola Richard Faruwa, and Yan Zhang. "Borehole resistivity and induced polarization tomography at the Canadian Shield for Mineral Exploration in north-western Sudbury." E3S Web of Conferences 168 (2020): 00002. http://dx.doi.org/10.1051/e3sconf/202016800002.
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Mineral exploration in the Canadian shield is a major challenge nowadays. This is because of the thick overburden cover and complex geology. Borehole tomography using resistivity and induced polarization (BHDCIP) method has a big advantage here due to that the data is acquired underneath the cover and data quality, in general, is superior to that acquired at the surface. BHDCIP provides good resistivity and chargeability data, which can identify mineralization easily. In this study, the BHDCIP survey with high-resolution data was carried out to identify mineralization zones in the McCreedy West zone, north-western Sudbury, Ontario, Canada. Two and three-dimensional (2-D and 3-D) inversion results of three boreholes clearly revealed the mineralization zones and that harmonised with previous geological studies in the study area. The BHDCIP method provided insight and developed an informative subsurface map to identify the mineralization zones, thus proving it as a beneficial tool used for mineral exploration in complex geology with a minimal data survey and an irregular geometrical distribution.
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Peacey, Vicky, Ernest K. Yanful, and Roger Payne. "Field study of geochemistry and solute fluxes in flooded uranium mine tailings." Canadian Geotechnical Journal 39, no. 2 (April 1, 2002): 357–76. http://dx.doi.org/10.1139/t01-097.
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A geochemical investigation was conducted at the Quirke cell 14 mine waste management area near Elliot Lake, Ontario, Canada, to assess the evolution of water quality of submerged preoxidized uranium mine tailings. Dissolved solids, sulphate, and radium fluxes towards the water cover were calculated using measured solute concentrations, water-cover volumes, and seepage rates for 1993 and 1999. Results indicate that flooding of preoxidized tailings can lead to the initial release of dissolved solids, acidity, and sulphate from the tailings to the overlying water cover. However, the overall impact of this release on the water cover can be minimal in the long term because of dilution from precipitation and fresh water inflows and flushing of the oxidation products down into the pore water. Profiles of dissolved metals and sulphate across the tailingswater interface at the study site indicated a high degree of chemical stability. Solute concentrations in the water cover were homogeneous and generally low at all stations. Pore-water profiles revealed minor remobilization of some trace metals and radionuclides in the shallow pore water (~0.15 m).Key words: mine tailings, water cover, pore-water geochemistry, radium, metal mobility, diffusion, flux.
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Quigley, R. M., A. J. Sethi, P. Boonsinsuk, D. E. Sheeran, and R. N. Yong. "Geologic control on soil composition and properties, Lake Ojibway clay plain, Matagami, Quebec." Canadian Geotechnical Journal 22, no. 4 (November 1, 1985): 491–500. http://dx.doi.org/10.1139/t85-069.
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Varved clays deposited in proglacial Lake Ojibway at Matagami, Quebec, were derived from two source areas: carbonate-deficient, Precambrian crystalline igneous rocks from New Quebec to the east and carbonate-rich Palaeozoic rocks from the James Bay lowlands in Ontario to the west. About 50% of the 12–15 m thick clay section consists of varved clays containing less than 3% carbonate, reflecting the New Quebec source. The remaining 50% of the section consists of two pulses of carbonate-enriched varves (15–30% carbonate) derived from rock flour in two glacial advances known as Cochrane I and Cochrane II, which advanced to within 20 km of Matagami.The clays are preconsolidated at the site by a combination of desiccation, groundwater level drawdown, and bonding, in such a way that σp′ is almost constant at 70 kPa at depths from 3.5 to 10 m.High in situ water contents correlate with thinner, low-carbonate, distal varves of high activity. The est correlations are obtained for relative activity, Ac(rel), defined as plasticity index ÷ specific surface area (Ip ÷ SS). Carbonate seems to have effectively neutralized smectite in the Cochrane proximal varves, rendering the distal varves (of New Quebec source) the most active clays at the site. Key words: varved clay, activity, carbonate, turbidity currents, glacial geology.
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Rowe, R. Kerry, Chris J. Caers, and Frank Barone. "Laboratory determination of diffusion and distribution coefficients of contaminants using undisturbed clayey soil." Canadian Geotechnical Journal 25, no. 1 (February 1, 1988): 108–18. http://dx.doi.org/10.1139/t88-011.
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This paper describes a technique for determining the diffusion coefficient and the distribution coefficient for contaminants using saturated, intact (undisturbed) clayey soil samples. The technique is illustrated with reference to a number of laboratory tests involving advective-diffusive migration of potential contaminants through an intact clayey soil from Sarnia, Ontario. An important aspect of the proposed technique is that the mass of contaminant in the system is kept constant and so significant decrease in source leachate concentration occurs during each test. A simple theoretical model is used to analyze this case and it is shown that this phenomenon can be used to deduce both the diffusion coefficient and the distribution/partitioning coefficient from a single test. Parameters are deduced for a number of salt solutions passing through the clay from the Sarnia area. On the basis of these tests it is suggested that for the Sarnia soil and advective velocities up to the maximum examined (0.035 m/a), mechanical dispersion does not measurably affect the magnitude of the "coefficient of hydrodynamic dispersion" (i.e., there is no significant dispersion). It is also suggested that the effective porosity corresponds to that deduced from the water content of the soil. Key words: contaminant migration, soil, laboratory study, experimental, analysis, diffusion, advection, clays, groundwater.
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Lowell, Thomas V., and Timothy G. Fisher. "Reply to comments by Carlson et al., (2009) on “Radiocarbon deglaciation chronology of the Thunder Bay, Ontario area and implications for ice sheet retreat patterns”." Quaternary Science Reviews 28, no. 23-24 (November 2009): 2548–50. http://dx.doi.org/10.1016/j.quascirev.2009.06.022.
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McNaughton, Kimberly A., and Peter F. Lee. "Water Quality Effects from an Aquaculture Operation in a Meromictic Iron Pit Lake in Northwestern Ontario, Canada." Water Quality Research Journal 45, no. 1 (February 1, 2010): 13–24. http://dx.doi.org/10.2166/wqrj.2010.003.
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Abstract In 1989, aquaculture for the production of rainbow trout (Oncorhynchus mykiss) was started in the upper depths of the 180-m deep Caland pit lake formed after the flooding of the former Steeprock Iron Mine. After ten years of operation, water quality was shown to be affected by the fish farm as well as proximal waste and the surficial geology of the area. Meromictic conditions occurred in the pit lake with a dichotomy in water quality versus depth. A cluster of parameters (ammonia, total phosphorus, total Kjeldahl nitrogen, dissolved organic carbon, B, pH, dissolved oxygen) were either in higher concentrations in the mixolimnion or varied little throughout the entire water column, and a second cluster of parameters had higher levels below the chemocline (conductivity, alkalinity, dissolved inorganic carbon, total dissolved solids, nitrate, sulfate, Ca, Mg, hardness, Na, Cl, K, Fe, Mn, Sr, and silicon dioxide). Statistically significant variations in concentrations among many of these chemical parameters were observed between the two years of study, among depths, and among seasons. Nutrient loading from excess fish food and waste increased phosphorus and ammonia levels. The expansion of the fish farm also reduced the levels of dissolved oxygen in the lower depths of the pit lake, thus reducing the volume of usable water for aquaculture purposes. In the early 2000s the fish farm decreased production and those closed in 2006. Later data showed that nitrate and potassium had corresponding decreases in both the monimolimnion and the mixolimnion. Sulfate levels remained elevated.
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Harvey, Robert Richard, and Edward Arthur McBean. "Comparing the utility of decision trees and support vector machines when planning inspections of linear sewer infrastructure." Journal of Hydroinformatics 16, no. 6 (May 12, 2014): 1265–79. http://dx.doi.org/10.2166/hydro.2014.007.
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Closed-circuit television inspection technology is traditionally used to identify aging sewer pipes requiring rehabilitation. While these inspections provide essential information on the condition of pipes hidden from day-to-day view, they are expensive and often limited to small portions of an entire sewer system. Municipalities may benefit from utilizing predictive analytics to leverage existing inspection datasets so that reliable predictions of condition are available for pipes that have not yet been inspected. The predictive capabilities of data mining systems, namely support vector machines (SVMs) and decision tree classifiers, are demonstrated using a case study of sanitary sewer pipe inspection data collected by the municipality of Guelph, Ontario, Canada. The modeling algorithms are implemented using open-source software and are tuned to counteract the negative impact on predictive performance resulting from class imbalance common within pipe inspection datasets. The decision tree classifier outperforms SVM for this classification task – achieving an acceptable area under the receiver operating characteristic curve of 0.77 and an overall accuracy of 76% on a stratified test set. Although predicting individual pipe condition is a notoriously difficult task, decision trees are found to be a useful screening tool for planning future inspection-related activities.
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Henriksen, A., P. J. Dillon, and J. Aherne. "Critical loads of acidity for surface waters in south-central Ontario, Canada: regional application of the Steady-State Water Chemistry (SSWC) model." Canadian Journal of Fisheries and Aquatic Sciences 59, no. 8 (August 1, 2002): 1287–95. http://dx.doi.org/10.1139/f02-092.
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Critical loads of acidity and the amount by which these critical loads are exceeded by atmospheric deposition (termed "exceedances") were estimated for 1469 lakes from five regions in south-central Ontario, Canada, using single lake chemistry measurements and sulphur deposition data for the period 19761999. Based on the Steady-State Water Chemistry (SSWC) model, four of the five regions had low critical loads, which is consistent with the underlying geology (silicate bedrock) and the thin glacial soils in these regions. Sulphur deposition in the study area showed a clear downward trend over the time period, with a decrease of approximately 50% to current levels of approximately 44 meq·m2·year1. As a result of the declining deposition, the portion of lakes with critical load exceedances has dropped substantially, from 7482% in the four sensitive regions in 1976 to 1126% in 1999. The pentile critical load is typically used as a regional target to account for uncertainties, but also to ensure that a sufficient percentage of lakes are protected (95%). This suggests that further reductions in emissions are required to reduce depositions to approximately 34 meq·m2·year1 (11 kg S·ha1·year1) to prevent critical load exceedance.
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Sakr, Mohammed, M. Hesham El Naggar, and Moncef Nehdi. "Novel toe driving for thin-walled piles and performance of fiberglass-reinforced polymer (FRP) pile segments." Canadian Geotechnical Journal 41, no. 2 (April 1, 2004): 313–25. http://dx.doi.org/10.1139/t03-089.
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Despite the rapidly growing use of pile foundations, it is presently difficult to assure the integrity and uniformity of the cross-sectional area of cast-in-place piles when using normal concrete. Cavities and soil encroachments leading to soil pockets can jeopardize their load-bearing capacity. Moreover, corrosion in reinforced concrete and steel shell piles has been very costly, exceeding US$2 billion in annual repair costs in the United States alone. To address these two challenges, extensive research has been underway at the University of Western Ontario to develop novel technology for the construction of piles. Self-consolidating concrete (SCC), a material that flows under gravity and assures the integrity of piles, is cast into fiberglass-reinforced polymer (FRP) tubes that provide corrosion-resistant reinforcement. A toe driving technique was developed to install the empty FRP shells into the soil, and SCC is subsequently cast into the shells. Driving tests using this new technique were carried out on large-scale model FRP and steel pipe piles installed in dense dry sand enclosed in a pressure chamber. FRPSCC and steel closed-end piles were also driven using conventional piling at the pile head. Static load tests were conducted on the various pile specimens under different vertical and horizontal confining pressures. The pile specimens were instrumented to investigate their dynamic behaviour under driving and their response to static compressive, uplift, and lateral loading. It is shown that the toe driving technique is very suitable for installing FRP piles in dense soils. Results from the driving tests and static load test indicate that FRPSCC hybrid piles are a very competitive and attractive option for the deep foundations industry.Key words: FRP, self-consolidating concrete, piles, pile drivability, toe driving, axial load, uplift load, lateral load, large-scale modeling, shaft resistance, dense sand.
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Zhdanov, Michael S., Xiaojun Liu, Glenn A. Wilson, and Le Wan. "3D migration for rapid imaging of total-magnetic-intensity data." GEOPHYSICS 77, no. 2 (March 2012): J1—J5. http://dx.doi.org/10.1190/geo2011-0425.1.
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Three-dimensional potential field migration for rapid imaging of entire total-magnetic-intensity (TMI) surveys is introduced, and real time applications are discussed. Potential field migration is based on a direct integral transformation of the measured TMI data into a 3D susceptibility model, which could be directly used for interpretation or as an a priori model for subsequent regularized inversion. The advantage of migration is that it does not require any a priori information about the type of the sources present, nor does it rely on regularization as per inversion. Migration is very stable with respect to noise in measured data because the transform is reduced to the downward continuation of a function that is analytical everywhere in the subsurface. The 3D migration of TMI data acquired over the Reid-Mahaffy test site in Ontario, Canada is used as a test study. Our results are shown to be consistent with those results obtained from 3D regularized inversion as well as the known geology of the area. Interestingly, the migration of raw TMI data produces results very similar to the inversion of diurnally corrected and microleveled TMI data, suggesting that migration could be applied directly to real-time imaging during the acquisition.
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Fernberg, P. A., C. Samson, D. H. Boteler, L. Trichtchenko, and P. Larocca. "Earth conductivity structures and their effects on geomagnetic induction in pipelines." Annales Geophysicae 25, no. 1 (February 1, 2007): 207–18. http://dx.doi.org/10.5194/angeo-25-207-2007.
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Abstract. Anomalous, large pipe-to-soil potentials (PSP) have been observed along a natural gas pipeline in eastern Ontario, Canada, where there is a major geological contact between the highly resistive rocks of the Precambrian Shield to the west and the more conductive Paleozoic sediments to the east. This study tested the hypothesis that large variations of PSP are related to lateral changes of Earth conductivity under the pipeline. Concurrent and co-located PSP and magnetotelluric (MT) geophysical data were acquired in the study area. Results from the MT survey were used to model PSP variations based on distributed-source transmission line theory, using a spatially-variant surface geoelectric field. Different models were built to investigate the impact of different subsurface features. Good agreement between modelled and observed PSP was reached when impedance peaks related to major changes of subsurface geological conditions were included. The large PSP could therefore be attributed to the presence of resistive intrusive bodies in the upper crust and/or boundaries between tectonic terranes. This study demonstrated that combined PSP-MT investigations are a useful tool in the identification of potential hazards caused by geomagnetically induced currents in pipelines.
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Scott, J. S., and R. A. Gibb. "Results of geoscience research in the Canadian Nuclear Fuel Waste Management Program: Introduction." Canadian Journal of Earth Sciences 26, no. 2 (February 1, 1989): 341–44. http://dx.doi.org/10.1139/e89-032.
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Canada, along with other countries that are considering the permanent disposal of high-level radioactive wastes from nuclear power generation, is undertaking a program of research into deep geological disposal. This program, led by Atomic Energy of Canada Limited (AECL) with support from Energy, Mines and Resources Canada, other federal government departments, universities, and industrial consultants, has been in progress since early in 1973. Geoscience research, the subject of this symposium, complements research on fuel waste immobilization to provide the data and information essential to the design and assessment of a complete disposal concept involving both natural and engineered barriers to the migration of radioactive material from the waste vault.During the early phases of the program, prior to 1975, an evaluation of the potential of Canadian salt deposits for nuclear waste disposal, as well as a preliminary assessment of the suitability of other geological formations, was made. Because the Province of Ontario was, and remains, the principal region in Canada for nuclear power development and because resources available for geoscience research would not permit simultaneous, intensive research on a number of rock types, the decision was taken to direct the main thrust of the geoscience research toward plutonic igneous rocks of the Canadian Shield in Ontario (Scott 1979). Lesser studies of salt and other sedimentary formations, including seabed, are continuing within the Geological Survey of Canada.Because the rock mass surrounding the vault will provide the principal barrier to the migration of radionuclides, should these be released from the emplaced wastes, knowledge and understanding of potential pathways through the rock mass and of the mechanisms of radionuclide transport and retention within the rock mass over the functional lifetime of the vault are fundamental requirements.Accordingly, the objectives of the geoscience research program (Dormuth and Scott 1984) are the following:(1) Develop and apply techniques to define the physical and chemical properties of large rock masses and of fluids within these rock masses.(2) Use these techniques in selected field research areas to calibrate and evaluate models developed to calculate fluid flow and mass transport through a large rock mass containing a hypothetical underground nuclear fuel waste-disposal vault.(3) Establish procedures to evaluate quantitatively rock bodies for their potential as disposal sites and thereby acquire the capability to compare different rock bodies.(4) Determine the long-term stability of plutonic rock masses by assessing the potential disturbance by seismic activity, glaciation, meteorite impact, and other disruptive events and processes.To achieve these objectives it has been necessary to undertake simultaneously a large number of research tasks involving the disciplines of geology, geophysics, hydrogeology, geomechanics, geochemistry, and mathematics. Some of these tasks are concerned primarily with regional aspects of the Canadian Shield, such as stress distribution, glaciation, and tectonic history; others with details of the surface and subsurface geology and hydrogeology of specific field research areas; and still others with the development and application of exploration technology to detect and evaluate the structural characteristics of igneous rock masses of relatively high integrity and uniformity. Field and office studies are supported by laboratory investigations of the physical and chemical properties of plutonic rocks, with specific reference to origin, history, and ability to retard or transmit radionuclides.Deep exploratory drilling and detailed surface mapping are carried out at designated field research areas in the Canadian Shield. Geoscience work at research areas has the two-fold purpose of (i) testing new and existing exploration techniques for the evaluation of rock masses; and (ii) through application of these airborne, surface, and subsurface techniques, providing the field data necessary for the development of concepts and models that form the basis for establishing site-selection criteria and performing safety analyses.The latest research areas have been established at Atikokan, Ontario, an area underlain by granitic rocks, and at East Bull Lake north of Massey, Ontario, where gabbroic rocks are the dominant type. These research areas complement previously established research areas developed on granitic rocks at AECL properties at Chalk River, Ontario, and Pinawa, Manitoba, and at a research area, also on granitic terrane, near White Lake, Ontario, where work was done early in the program to test geophysical exploration and borehole-logging equipment.The ability to predict subsurface geological and hydrogeological conditions at future waste-disposal sites is one of the primary goals of geoscience research in the Canadian Nuclear Fuel Waste Management Program (CNFWMP). One of the most important program elements designed to test this predictive capability was the construction of the Underground Research Laboratory (URL) in the Lac du Bonnet Batholith near the site of the Whiteshell Nuclear Research Establishment. Airborne, surface, and borehole methods were used to develop a geological model on the site, and hydrogeological investigations were carried out to establish preconstruction groundwater characteristics. As the excavation of the URL facilities proceeded, the geological features encountered and the changes in the hydrogeological systems were carefully monitored. These data are being used to assess and improve the geological and hydrogeological models being developed for the rock mass surrounding the URL.The URL provides an excellent opportunity to (i) study the effect of excavation techniques, heat, and stress on a rock mass; (ii) simulate and study the complex systems that may exist in a disposal vault environment; and (iii) develop and test shaft- and drift-sealing techniques. Recently, a bilateral agreement between AECL and the United States Department of Energy was signed for co-operative research on nuclear fuel waste disposal. A substantial part of this co-operative effort will be directed toward extension of the URL shaft beyond its present depth of 240 m and conducting a variety of nonnuclear experiments within the shaft and excavated chambers of the URL.From the time of formalization of CNFWMP over 10 years ago, a concerted effort has been made by AECL and other program participants to ensure both peer review of and widespread accessibility to results of research arising from CNFWMP. This symposium is the third to be sponsored by the Geological Association of Canada (GAC)—the two previous symposiums were held at GAC annual meetings in Winnipeg in 1982 and Toronto in 1978. In addition to these major symposia, general information meetings sponsored by AECL have been held annually at various centres across Canada, and research elements of CNFWMP formed a significant part of the technical program for an international meeting held by the Canadian Nuclear Society in Winnipeg in September 1986.Since 1979 the CNFWMP review process has been further enhanced by the Technical Advisory Committee chaired by L. W. Shemilt, McMaster University. This committee, comprising members nominated by major Canadian scientific and technical societies including the Canadian Geoscience Council, has annually provided a publicly available report of constructive criticism and recommendations for improvement in the research content of CNFWMP.During the second half of 1988 it is expecte
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MacCormack, Kelsey, Emmanuelle Arnaud, and Beth L. Parker. "Using a multiple variogram approach to improve the accuracy of subsurface geological models." Canadian Journal of Earth Sciences 55, no. 7 (July 2018): 786–801. http://dx.doi.org/10.1139/cjes-2016-0112.
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Subsurface geological models are often used to visualize and analyze the nature, geometry, and variability of geologic and hydrogeologic units in the context of groundwater resource studies. The development of three-dimensional (3D) subsurface geological models covering increasingly larger model domains has steadily increased in recent years, in step with the rapid development of computing technology and software, and the increasing need to understand and manage groundwater resources at the regional scale. The models are then used by decision makers to guide activities and policies related to source water protection, well field development, and industrial or agricultural water use. It is important to ensure that the modelling techniques and procedures are able to accurately delineate and characterize the heterogeneity of the various geological environments included within the regional model domain. The purpose of this study is to examine if 3D stratigraphic models covering complex Quaternary deposits can be improved by splitting the regional model into multiple submodels based on the degree of variability observed between surrounding data points and informed by expert geological knowledge of the geological–depositional framework. This is demonstrated using subsurface data from the Paris Moraine area near Guelph in southern Ontario. The variogram models produced for each submodel region were able to better characterize the data variability, resulting in a more geologically realistic interpolation of the entire model domain as demonstrated by the comparison of the model output with preexisting maps of surficial geology and bedrock topography as well as depositional models for these complex glacial environments. Importantly, comparison between model outputs reveals significant differences in the resulting subsurface stratigraphy, complexity, and variability, which would in turn impact groundwater flow model predictions.
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MacLeod, Josef, Wendel (Bill) Keller, Andrew M. Paterson, Richard D. Dyer, and John M. Gunn. "Scale and watershed features determine lake chemistry patterns across physiographic regions in the far north of Ontario, Canada." Journal of Limnology, November 8, 2016. http://dx.doi.org/10.4081/jlimnol.2016.1553.
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<p>Changes in the far north of Ontario (>50°N latitude), like climate warming and increased industrial development, will have direct effects on watershed characteristics and lakes. To better understand the nature of remote northern lakes that span the Canadian Shield and Hudson Bay Lowlands, and to address the pressing need for limnological data for this vast, little-studied area of Ontario, lake chemistry surveys were conducted during 2011-2012. Lakes at the transition between these physiographic regions displayed highly variable water chemistry, reflecting the peatland landscape with a mix of bog and fen watersheds, and variations in the extent of permafrost. In the transition area, Shield and Lowlands lakes could not be clearly differentiated based on water chemistry; peat cover decouples, to varying degrees, the lakes from the influences of bedrock and surficial deposits. Regional chemistry differences were apparent across a much broader area of northern Ontario, due to large-scale spatial changes in geology and in the extent of peatlands and permafrost. Shield lakes in the far northwest of Ontario had Ca, Mg, and TP concentrations markedly higher than those of many Lowlands lakes and previously studied Shield lakes south of 50°N, related to an abundance of lacustrine and glacial end-moraine deposits in the north.</p>
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Sarkar, Grytan, and Abouzar Sadrekarimi. "Cyclic Shearing Behavior and Dynamic Characteristics of a Fibrous Peat." Canadian Geotechnical Journal, August 5, 2021. http://dx.doi.org/10.1139/cgj-2020-0516.
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Cyclic shearing behavior, dynamic characteristics, and post-cyclic volume change of a peat sublayer from the Port Lands area of Toronto (Ontario, Canada) are investigated in this study. Laboratory specimens are trimmed from block samples collected from a depth of about 4.0 to 4.5 m. Constant-volume cyclic direct simple shear tests indicate an initial reduction of effective stress with number of stress cycles. However, the corresponding excess pore pressure ratios do not exceed 60%, indicating a cyclic mobility behavior in the peat specimens. Maximum shear moduli of the peat samples are also determined from shear wave velocity measurements. Post-cyclic volumetric strain, as well as the variations of secant modulus, modulus reduction, and damping ratio of the peat are presented in terms of cyclic shear strain and compared with other studies. Empirical relationships are proposed for characterizing the shear modulus and damping ratio of Toronto peat.
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Naprstek, Tomas, and Richard Smith. "Convolution Neural Networks Applied to the Interpretation of Lineaments in Aeromagnetic Data." GEOPHYSICS, September 22, 2021, 1–50. http://dx.doi.org/10.1190/geo2020-0779.1.
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Parameter estimation in aeromagnetics is an important tool for geological interpretation. Due to aeromagnetic data being highly prevalent around the world, it can often be used to assist in understanding the geology of an area as a whole, or for locating potential areas of further investigation for mineral exploration. Methods that automatically provide information such as the location and depth to the source of anomalies are useful to the interpretation, particularly in areas where a large number of anomalies exist. Unfortunately, many of the current methods rely on high-order derivatives, and are therefore susceptible to noise in the data. Convolution neural networks (CNNs) are a subset of machine learning methods that are well-suited to image processing tasks, and have been shown to be effective at interpreting other geophysical data, such as seismic sections. Following several similar successful approaches, we have developed a CNN methodology for estimating the location and depth of lineament-type anomalies in aeromagnetic maps. To train the CNN model, we utilized a synthetic aeromagnetic data modeler to vary relevant physical parameters, and developed a representative dataset of approximately 1.4 million images. These were then used for training classification CNNs, with each class representing a small range of depth values. We first applied the model to a series of difficult synthetic datasets with varying amounts of noise, comparing the results against the tilt-depth method. We then applied the CNN model to a dataset from north-eastern Ontario, Canada, that contained a dyke with known depth, which was correctly estimated. This method is shown to be robust to noise, and can easily be applied to new datasets using the trained model, which has been made publicly available.