From 1 - 10 / 25
  • As part of the International Polar Year (IPY) 2007'08 and 2008'09 activities, and related objectives of the Commission for the Geological Map of the World (CGMW), nations of the circumpolar Arctic have co-operated to produce a new bedrock geology map and related digital map database at a scale of 1:5 000 000. The map, released in north polar stereographic projection using the World Geodetic System (WGS) 84 datum, includes complete geological and physiographic coverage of all onshore and offshore bedrock areas north of latitude 60° north.

  • The data presented in the radioactivity map of Canada series (Buckle et al., 2014) depict the surface concentrations of three naturally-occurring radioactive elements: potassium (K, %), equivalent uranium (eU, ppm), and equivalent thorium (eTh, ppm); as well as five derived products: natural air absorbed dose rate (NADR, nGy/h) calculated from a linear combination of potassium, equivalent uranium, and equivalent thorium concetrations; the ratios eU/eTh, eU/K, and eTh/K; and the ternary map which uses false colour to illustrate the co-variation of the three measured elements (Broome et al., 1987). This compilation was produced with data from more than 370 airborne gamma-ray surveys flown or supervised by the Geological Survey of Canada between 1969 and 2011. Data was calibrated and acquired in accordance to standards in effect at the time each survey (see Darnley et al., 1975 and IAEA, 1991). Most of the data was acquired using 50 L of Sodium Iodide (NaI) detectors flown at a nominal terrain clearance of 120 m, but line spacings vary from 5000 m to 200 m depending on the specific survey. Potassium is measured directly from the 1460 keV gamma-ray photons emitted by Potassium-40. Uranium and thorium, however, are determined indirectly from gamma-ray photons emitted by daughter products Bismuth-214 (1765 keV) and Thallium-208 (2614 keV) respectively assuming equilibrium between daughter and parent isotopes. For this reason, gamma-ray spectrometric measurements of uranium and thorium are referred to as equivalent uranium (eU) and equivalent thorium (eTh). The measured gamma-rays originate from geological materials in the upper 30 cm of the Earth's surface and their intensity are directly related to the concentrations of K, U and Th in the rocks and minerals present. The geochemical information presented in this compilation is used to support bedrock and surficial geology mapping by outlining lithological variations. It can also indicate mineralization either by association of radio-elements as trace elements with economic minerals or through delineation of their enrichment or depletion due to geochemical alteration resulting from mineralization processes. Overall, this information also contributes to the characterization of the natural radiation environment. Futher information on data acquisition, processing and interpretation and on application can be found in IAEA-TECDOC-1363 (2003), and references therein. These data were also published as Geological Survey of Canada maps, in the Open Files series (7396-7403). References Broome, J., J.M. Carson, J.A. Grant, and K.L. Ford, 1987. A modified ternary radioelement mapping technique and its application to the south coast of Newfoundland, Geological Survey of Canada, Paper 87-14. https://doi.org/10.4095/122382 Buckle, J.L., J.M. Carson, K.L. Ford, R. Fortin and W.F. Miles, 2014, Radioactivity map of Canada, ternary radioelement map, Geological Survey of Canada, Open File 7397. https://doi.org/10.4095/293354 Darnley, A.G., E. M. Cameron and K. A. Richardson, 1975. The Federal-Provincial Uranium Reconnaissance Program, in Geological Survey of Canada, Paper 75-26, p. 49-71. https://doi.org/10.4095/102591 International Atomic Energy Agency, 1991. Airborne Gamma Ray Spectrometer Surveying, International Atomic Energy Agency, Technical Reports Series No. 323. https://www.iaea.org/publications/1427/airborne-gamma-ray-spectrometer-surveying International Atomic Energy Agency, 2003. Guidelines for radioelement mapping using gamma ray spectrometry data; International Atomic Energy Agency, Technical Reports Series No. 1363. https://www.iaea.org/publications/6746/guidelines-for-radioelement-mapping-using-gamma-ray-spectrometry-data

  • Categories  

    This entry provides access to surficial geology maps that have been published by the Geological survey of Canada. Two series of maps are available: "A Series" maps, published from 1909 to 2010 and "Canadian Geoscience Maps", published since 2010. Three types of CGM-series maps are available: 1)Surficial Geology: based on expert-knowledge full air photo interpretation (may include interpretive satellite imagery, Digital Elevation Models (DEM)), incorporating field data and ground truthing resulting from extensive, systematic fieldwork across the entire map area. Air photo interpretation includes map unit/deposit genesis, texture, thickness, structure, morphology, depositional or erosional environment, ice flow or meltwater direction, age/cross-cutting relationships, landscape evolution and associated geological features, complemented by additional overlay modifiers, points and linear features, selected from over 275 different geological elements in the Surficial Data Model. Wherever possible, legacy data is also added to the map. 2)Reconnaissance Surficial Geology: based on expert-knowledge full air photo interpretation (may include interpretive satellite imagery, DEMs), with limited or no fieldwork. Air photo interpretation includes map unit/deposit genesis, texture, thickness, structure, morphology, depositional or erosional environment, ice flow or meltwater direction, age/cross-cutting relationships, landscape evolution and associated geological features, complemented by additional overlay modifiers, points and linear features, selected from over 275 different geological elements in the Surficial Data Model. Wherever possible, legacy data is also added to the map. 3)Predictive Surficial Geology: derived from one or more methods of remote predictive mapping (RPM) using different satellite imagery, spectral characteristics of vegetation and surface moisture, machine processing, algorithms etc., DEMs, where raster data are converted to vector, with some expert-knowledge air photo interpretation (training areas or post-verification areas), varying degrees of non-systematic fieldwork, and the addition of any legacy data available. Each map is based on a version of the Geological Survey of Canada's Surficial Data Model (https://doi.org/10.4095/315021), thus providing an easily accessible national surficial geological framework and context in a standardized format to all users. "A series" maps were introduced in 1909 and replaced by CGM maps in 2010. The symbols and vocabulary used on those maps was not as standardized as they are in the CGM maps. Some "A series" maps were converted into, or redone, as CGM maps, Both versions are available whenever that is the case. In addition to CGM and "A series" maps, some surficial geology maps are published in the Open File series. Those maps are not displayed in this entry, but can be found and accessed using the NRCan publications website, GEOSCAN:(https://geoscan.nrcan.gc.ca).

  • Categories  

    To support improved groundwater geoscience knowledge for southern Ontario, a regional 3-D model of the surficial geology of southern Ontario has been developed as a part of a collaboration between the Ontario Geological Survey and the Geological Survey of Canada. Covering approximately 66,870 km2 in area, the model is a synthesis of existing geological models, surficial geology mapping, and subsurface data. The model is a simplified 9-layer reclassification of numerous mapped local surficial sediment formations in places over 200 m thick with a total volume of approximately 2,455 km3. The model integrates 1:50,000 scale surficial geology mapping with 90 m bathymetrically corrected topographic digital elevation model (DEM) and 8 existing local 3-D models. Archival subsurface data include 10,237 geotechnical and stratigraphic boreholes, 3,312 picks from geophysical surveys, 15,902 field mapping sites and sections, 537 monitoring and water supply wells and 282,995 water well records. Roughly corresponding to regional aquifer and aquitard layers, primary model layers are (from oldest to youngest): Bedrock, Basal Aquifer, Lower Sediment, Regional Till, Post Regional Till Channel Fill, Glaciofluvial Sediment, Post Regional Till Mud, Glaciolacustrine Sand and Recent Sediment / Organics. Modelling was completed using an implicit modelling application (LeapFrog®) complemented by an expert knowledge approach to data classification and rules-based Expert System procedure for data interpretation and validation. An iterative cycle of automated data coding, intermediate model construction and manual data corrections, expert evaluations, and revisions lead to the final 3-D model. A semi-quantitative confidence assessment has been made for each model layer surface based on data quality, distribution and density. This surficial geology model completes the development of a series of regional 3-D geological and hydrogeological models for southern Ontario.

  • The compilation represents publicly available reports of geochronological information for Canada. This includes federal, provincial and territorial government publications and reports, university theses, books and journals. Current coverage is limited to those areas that have been the target of recent past compilation efforts, with other areas and updates being included as they become ready. Users should be aware that the compilation may not include all available data for a given area. Every effort is made to report the ages without reinterpreting the original authors' intent. However, care has also been taken to highlight the salient features of the data by which the end-user can make initial judgment on the data robustness. Users are cautioned that because of space limitations and the necessary summarization of often complex datasets, that the original publication should be consulted to verify age interpretations and their rationale. Data may be extracted by the user in tab-delimited text format.

  • The data used in this compilation come from the Canadian Gravity Database (CGDB), which is managed by the Canadian Geodetic Survey (CGS), Surveyor General Branch. CGDB includes more than 755 000 observations, including some 232 000 observations on land. The distribution of the land data represents an average of one gravity point per 40 km². The gravity maps, which are gridded to a 2-km interval with a blanking radius of 20 km, currently include data acquired between 1944 and 2015. CGS and partners continue to supplement the CGDB each year. The surveys are conducted using relative gravimeters that measure the gravity difference between two locations. On the landmass, gravity has been measured primarily using static gravimeters. Although measurements at some offshore locations have been collected using static gravimeters on the ocean floor, most are acquired using dynamic gravimeters aboard moving vessels. The relative nature of the gravimeters require that surveys be tied to base (control) stations with known absolute gravity. The base stations are part of the Canadian Gravity Standardization Network (CGSN), which is tied to the International Gravity Standardization Network 1971 (IGSN71). Today, the traditional base stations are being replaced by new base stations that are measured with an absolute gravimeter having an accuracy of 2µGal (2x10-8 m/s²). All relative gravity measurements are integrated into the IGSN71 datum to create a coherent dataset at the global scale. Normal (theoretical) gravity is calculated using the Geodetic Reference System 1980 (GRS80; https://doi.org/10.1007%2FS001900050278). Bouguer anomalies, which include reductions of the elevation and topographical mass to sea level, are calculated using a vertical gravity gradient of ~0.3086 mGal/m (change slightly with latitude and elevation) and a crustal density of 2670 kg/m³.

  • This data set is a compilation of data acquired mostly by airborne surveys in Canada, gridded at 200 m and 1 km resolutions. The Geological Survey of Canada has flown or supervised more than 700 surveys since 1947, generally with a flight-line spacing of 800 m and an altitude of 305 m above the ground, though since 2000 the majority of surveys have been flown with a line spacing of 400 m or less. These aeromagnetic surveys have been leveled to each other to correct for arbitrary datums, slow variations of Earth's magnetic field over time, and differing survey specifications. The magnetic character of a rock depends on its ferromagnetic mineral composition, its concentration and its deformational and metamorphic history. Variations in the magnetic character of Earth's crust cause small magnetic anomalies in the earth's magnetic field. These magnetic anomalies can show geological trends and structural boundaries. The first vertical derivative of magnetic anomalies is calculated from the residual magnetic field and enhances the short wavelength component of the field. It is often used to trace contacts between magnetic domains. These data have also been published as two Geological Survey of Canada Open File maps: Magnetic Anomaly Map, Canada, (Open File 7799) and the First Vertical Derivative of the Magnetic Anomalies Map, Canada, (Open File 7878).

  • Categories  

    The "Canadian Database of Geochemical Surveys" has two long-term goals. Firstly, it aims to catalogue all of the regional geochemical surveys that have been carried out across Canada, beginning in the 1950s. Secondly, it aims to make the raw data from those surveys available in a standardised format. Over 1,500 surveys have been catalogued. Of these, the raw data for over 300 have been converted to a standardised format. The catalogue can be searched at https:\\geochem.nrcan.gc.ca

  • Categories  

    A collection of magnetotelluric surveys performed by the Geological Survey of Canada from 1987 to 2018.

  • High resolution 2D/3D seismic surveys performed for the Geological Survey of Canada to advance the use of seismic methods in hard rock environments.