Identification_Information: Citation: Citation_Information: Originator: Kjarsgaard, B.A. Originator: Wilkinson, L. Originator: Armstrong, J.A. Publication_Date: 2002 Title: Lac de Gras kimberlite field, central Slave Province Edition: 1.0 Geospatial_Data_Presentation_Form: vector digital data Series_Information: Series_Name: Open File Issue_Identification: 3238 Publication_Information: Publication_Place: Ottawa, Ontario Publisher: Geological Survey of Canada, Natural Resources Canada Other_Citation_Details: Recommended citation: 2002: Kjarsgaard, B.A., Wilkinson, L., and Armstrong, J.A., 2002. Geology, Lac de Gras kimberlite field, central Slave Province, Northwest Territories–Nunavut; Geological Survey of Canada, Open File 3238, scale 1:250 000. Online_Linkage: Description: Abstract: The Eocene to Cretaceous Lac de Gras kimberlite field occurs in the central Slave Province. The bedrock geology map compilation area, which encompasses the Lac de Gras kimberlite field, includes the NTS sheets 76C (Aylmer Lake), 76D (Lac de Gras), 76E (Contwoyto Lake, south half) and 76F (Nose Lake, south west corner). The main bedrock geological elements within the map area are shown in Figure 1: 1.) Pre- to syn-Yellowknife Supergroup gneiss, migmatite and metagranitoid rocks; 2.) Yellowknife Supergroup volcanic and volcaniclastic rocks, and syn-Yellowknife Supergroup felsic porphyritic and mafic intrusive rocks; 3.) Yellowknife Supergroup sedimentary rocks; 4.) Syn-Yellowknife Supergroup granitoid rocks 5.) Post-Yellowknife Supergroup granites; 6.) Proterozoic intrusions (dominantly diabase dykes); 7.) Eocene to Cretaceous kimberlite pipes. The geology of the area is described and discussed in terms of the seven main bedrock elements, with some additional notes on structure, metamorphism, and economic geology. The map and marginal notes are compiled from previously published bedrock geology maps and accompanying marginal notes, with these sources shown in Figure 2. In addition, papers and reports on specific aspects of the geology of the compilation area were also utilized. A number of problems are inherent in creating a bedrock compilation map, in which the original individual maps were generated over a period of greater than fifty years. The map legend is based upon the mineralogical description of the pertinent rock unit, not how that unit was originally named. This was done, in part, to eliminate rock unit name conflicts at map boundaries e.g. what one geologist describes as a tonalite, on an adjacent map (within a contiguous granitoid pluton) another geologist might describe as a quartz diorite . For the Aylmer Lake map sheet (Lord and Barnes, 1954) and the southeast quadrant of the Lac de Gras map sheet (Folinsbee, 1949) mineralogical descriptions were extracted from the archived field notebooks in conjunction with the traverse maps. This information was then utilized to subdivide and place the syn- and post-Yellowknife Supergroup granitoids into a modern context. Were possible, this was confirmed by examining archived rock samples. Verification of this approach has further been confirmed from sampling of granitoid rocks in the Aylmer Lake map sheet (K. MacLachlan and B. Davis, personal communication, 2001). The surficial geology of the area (with the exception of the Nose Lake map sheet) has been mapped within the past decade (see Dredge et al., 1995a; Kerr et al., 1997; Ward et al., 1997). Additional information on till geochemistry, and gold grain counts in till can be found in Dredge et al. (1995b), Ward et al. (1996) and Dredge et al. (1997). Results from low-density kimberlite indicator mineral sampling (grain counts and chemistry) are reported in Dredge et al. (1995c) and Ward et al. (1995). McClenaghan et al. (2000) provide a detailed study of the down ice dispersion train from the Ranch Lake kimberlite (till geochemistry, grain counts and mineral chemistry). Armstrong (2001) provides a comprehensive data set of industry kimberlite indicator grain counts and mineral chemistry for the area, based on information available in public domain assessment reports. Purpose: Supplemental_Information: Data set is in English. Magnetic declination stated in degrees and minutes. Annual change stated in minutes. Magnetic declination at NW corner of map: 23°25'E, changing 38'W annually. Magnetic declination at SW corner of map: 22°21'E, changing 34'W annually. Magnetic declination at NE corner of map: 19°5'E, changing 37'W annually. Magnetic declination at SE corner of map: 18°21'E, changing 32'W annually. Magnetic declination at center of map: 20°58'E, changing 36'W annually. Proximity of the North Magnetic Pole causes the compass to be erratic in this area. Number of base data sets used: 4 Base data set 1: Source is NTDB, ID is 76C, version n/a, n/a, scale 1:250000 Base data set 2: Source is NTDB, ID is 76D, version n/a, n/a, scale 1:250000 Base data set 3: Source is NTDB, ID is 76E, version n/a, n/a, scale 1:250000 Base data set 4: Source is NTDB, ID is 76F, version n/a, n/a, scale 1:250000 Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 2001 Range_of_Dates/Times: Beginning_Date: 1949 Ending_Date: 2001 Currentness_Reference: Field work years are 1949, 1954, 1956, 1976-1978, 1980, 1984, 1986-1991, 1993-1995, 1998, 1999, 2001. Compilation years are 2001. Status: Progress: Complete Maintenance_and_Update_Frequency: None Planned Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -112.000 East_Bounding_Coordinate: -108.000 North_Bounding_Coordinate: 65.500 South_Bounding_Coordinate: 64.000 Data_Set_G-Polygon: Data_Set_G-Polygon_Outer_G-Ring: G-Ring_Point: G-Ring_Latitude: 65.5000 G-Ring_Longitude: -111.6193 G-Ring_Point: G-Ring_Latitude: 65.5000 G-Ring_Longitude: -110.4999 G-Ring_Point: G-Ring_Latitude: 65.3758 G-Ring_Longitude: -110.1178 G-Ring_Point: G-Ring_Latitude: 65.2509 G-Ring_Longitude: -109.7400 G-Ring_Point: G-Ring_Latitude: 65.1309 G-Ring_Longitude: -109.3829 G-Ring_Point: G-Ring_Latitude: 65.0000 G-Ring_Longitude: -109.0000 G-Ring_Point: G-Ring_Latitude: 65.0000 G-Ring_Longitude: -108.0000 G-Ring_Point: G-Ring_Latitude: 64.4971 G-Ring_Longitude: -108.0000 G-Ring_Point: G-Ring_Latitude: 64.0000 G-Ring_Longitude: -108.0000 G-Ring_Point: G-Ring_Latitude: 64.0000 G-Ring_Longitude: -110.1860 G-Ring_Point: G-Ring_Latitude: 64.0000 G-Ring_Longitude: -112.0000 G-Ring_Point: G-Ring_Latitude: 64.6866 G-Ring_Longitude: -112.0000 G-Ring_Point: G-Ring_Latitude: 65.5000 G-Ring_Longitude: -112.0000 G-Ring_Point: G-Ring_Latitude: 65.5000 G-Ring_Longitude: -111.6193 Keywords: Theme: Theme_Keyword: geoscientificInformation Theme_Keyword: Geological and geophysical Theme_Keyword: Geology Theme_Keyword_Thesaurus: None Place: Place_Keyword: Contwoyto Lake Place_Keyword: Aylmer Lake Place_Keyword: Ghurka Lake Place_Keyword: Migration Lake Place_Keyword: MacKay Lake Place_Keyword: Courageous Lake Place_Keyword: Yamba Lake Place_Keyword: Pelonquin Lake Place_Keyword: Nunavut Place_Keyword: Northwest Territories Place_Keyword: Lac de Gras Place_Keyword_Thesaurus: None Access_Constraints: None Use_Constraints: Her Majesty the Queen in Right of Canada 2002 For more information, please contact the Copyright Officer at the following address: ESS Copyright Officer Business Development Office Earth Sciences Sector 615 Booth St., Ottawa, Ontario K1A 0E9 Sa Majesté la Reine du chef du Canada 2002 Pour plus d'information, prière de communiquer avec le responsable du droit d'auteur à l'adresse suivante : Responsable du droit d'auteur du SST Bureau d'expansion des affaires Secteur des sciences de la Terre 615, rue Booth Ottawa (Ontario) K1A 0E9 Point_of_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Bruce Kjarsgaard Contact_Organization: Natural Resources Canada Contact_Address: Address_Type: Physical Address: 601 Booth Street City: Ottawa State_or_Province: Ontario Postal_Code: K1A 0E8 Country: Canada Contact_Voice_Telephone: 613-995-5705 Contact_Facsimile_Telephone: 613-996-9820 Contact_Electronic_Mail_Address: bkjarsga@nrcan-rncan.gc.ca Data_Set_Credit: Additional geology by Bostock, H.H., Dillon-Leitch, H.C.H., Folinsbee, R.E., King, J.E., Relf, C., Davis, W.J., Lambert, M.B., LeCheminant, A.N., Lord, C.S., Barnes, F.Q., Moore, J.C.G., Renaud, J., Stubley, M., Thompson, P.H. and Kerswill, J.A. Digital cartography by Proulx, M. Data_Quality_Information: Lineage: Source_Information: Source_Scale_Denominator: 250000 Spatial_Data_Organization_Information: Direct_Spatial_Reference_Method: Vector Point_and_Vector_Object_Information: Spatial_Reference_Information: Horizontal_Coordinate_System_Definition: Planar: Grid_Coordinate_System: Grid_Coordinate_System_Name: Universal Transverse Mercator Universal_Transverse_Mercator: UTM_Zone_Number: 12 Transverse_Mercator: Scale_Factor_at_Central_Meridian: 0.9996 Longitude_of_Central_Meridian: -111 Latitude_of_Projection_Origin: 0.0 False_Easting: 500000.0 False_Northing: 0.0 Planar_Coordinate_Information: Planar_Coordinate_Encoding_Method: coordinate pair Coordinate_Representation: Abscissa_Resolution: 5 Ordinate_Resolution: 5 Planar_Distance_Units: meters Geodetic_Model: Horizontal_Datum_Name: North American Datum of 1983 Ellipsoid_Name: Geodetic Reference System 80 Semi-major_Axis: 6378137.0 Denominator_of_Flattening_Ratio: 298.25722209603690666513255949227 Distribution_Information: Distributor: Contact_Information: Contact_Person_Primary: Contact_Person: Mike Sigouin Contact_Organization: Natural Resources Canada Contact_Address: Address_Type: Physical Address: 601 Booth Street City: Ottawa State_or_Province: Ontario Postal_Code: K1A 0E8 Country: Canada Contact_Voice_Telephone: 613-943-0738 Contact_Facsimile_Telephone: 613-952-7308 Contact_Electronic_Mail_Address: msigouin@NRCan.gc.ca Resource_Description: Live Data and Maps Standard_Order_Process: Fees: None Metadata_Reference_Information: Metadata_Date: 20100914 Metadata_Future_Review_Date: 20150914 Metadata_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Paul Huppé Contact_Organization: Natural Resources Canada Contact_Address: Address_Type: Physical Address: 601 Booth Street City: Ottawa State_or_Province: Ontario Postal_Code: K1A 0E8 Postal_Code: K1A 0E8 Country: Canada Contact_Voice_Telephone: 613-943-0996 Contact_Facsimile_Telephone: 613-995-2339 Contact_Electronic_Mail_Address: huppe@NRCan.gc.ca Metadata_Standard_Name: FGDC Content Standard for Digital Geospatial Metadata Metadata_Standard_Version: FGDC-STD-001-1998