Description

This data set consists in a compilation of data acquired by aeromagnetic surveys in Canada, gridded at a 200 m and 1 km resolution. Magnetic anomalies show small variations in the magnetic field that are caused largely by variations in the magnetic properties of Earth's crust. The first vertical derivative of magnetic anomalies is calculated from the residual magnetic field and enhances the short wavelength component of the field. The magnetic character of a rock depends on its ferromagnetic mineral composition, its concentration and its deformational and metamorphic history. To map these variations, the Geological Survey of Canada has been acquiring aeromagnetic data since 1947. Over the years, more than 700 surveys have been carried out, 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 dominant structural trends of geological provinces, truncation of those trends at structural boundaries, and the characteristic patterns of suture zones can be recognized on the magnetic anomaly map. The magnetic signature of Precambrian basement rocks can be seen through the Phanerozoic sedimentary basin cover. Major dyke swarms can be traced over hundreds of kilometers from their radiating linear magnetic pattern. Oceanic crust has a characteristic striped magnetic pattern that is due to changes in the polarity of Earth's magnetic field, which occur over intervals of millions of years.

Resources

Name	Format	Description	Link
Canada - 1km - MAG - Residual Total Field	ZIP		http://gdr.agg.nrcan.gc.ca/gdrdap/dap/index-eng.php?dapid=129
Canada - 1km - MAG - 1st Vertical Derivative	ZIP		http://gdr.agg.nrcan.gc.ca/gdrdap/dap/index-eng.php?dapid=130
Canada - 200m - MAG - 1st Vertical Derivative	ZIP		http://gdr.agg.nrcan.gc.ca/gdrdap/dap/index-eng.php?dapid=138
Canada - 200m - MAG - Residual Total Field	ZIP		http://gdr.agg.nrcan.gc.ca/gdrdap/dap/index-eng.php?dapid=140
Canada - 1km - MAG - Metadata	HTML		http://gdr.agg.nrcan.gc.ca/gdrdap/dap/metadataquery_comb3.php?lang=eng&dapid=130
Canada - 200m - MAG - Metadata	HTML		http://gdr.agg.nrcan.gc.ca/gdrdap/dap/metadataquery_comb3.php?lang=eng&dapid=140
Canada - 1km - MAG - Metadata	HTML		http://gdr.agg.nrcan.gc.ca/gdrdap/dap/metadataquery_comb3.php?lang=fra&dapid=130
Canada - 200m - MAG - Metadata	HTML		http://gdr.agg.nrcan.gc.ca/gdrdap/dap/metadataquery_comb3.php?lang=fra&dapid=140
Magnetic anomaly map, Canada (Open File 7799)	PDF		https://doi.org/10.4095/297337
Magnetic anomaly map, Canada (Open File 7799)	PDF		https://geoscan.nrcan.gc.ca/starweb/geoscan/servlet.starweb?path=geoscan/fullf.web&search1=R=297337
Canadian Airborne Geophysical Database (CAGDB) Web service	WMS		http://wms.agg.nrcan.gc.ca/wms2/wms2.aspx?service=wms&version=1.3.0&request=GetCapabilities

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