Petersville mining district electromagnetic and magnetic airborne geophysical survey data compilation

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Frequently anticipated questions:


What does this data set describe?

Title:
Petersville mining district electromagnetic and magnetic airborne geophysical survey data compilation
Abstract:
The Petersville mining district electromagnetic and magnetic airborne geophysical survey geophysical survey is located approximately 40 kilometers west of Talkeetna, Alaska. Frequency domain electromagnetic and magnetic data were collected with the DIGHEMV system from October 1 to October 8, 1996. A total of 2967 line kilometers were collected covering 1075 square kilometers (km). Line spacing was 400 meters (m). Data were collected an average of 36 m above the ground surface from a helicopter towed sensor platform ("bird") on a 30 m long line. The data, as well as additional metadata, are available from the DGGS website: http://doi.org/10.14509/29445.
Supplemental_Information:
ascii_data:    ASCII format line data, other ASCII data	
databases_geosoft:    Geosoft format database of line data, other Geosoft format databases	
documents:    Project and field reports, survey background information, gridded data explanations, other supporting documentation	
grids_ermapper:    Geographically registered gridded data, ER Mapper ERS format	
grids_geosoft:    Geosoft-format binary grids, these grids can be viewed in ESRI ArcMap using a free plugin from Geosoft or using the free viewer available from Geosoft	
images_registered:    GeoTiff format images of all gridded data	
kmz:    Keyhole markup language (kml) kmz archive files of project data. Viewable in Google Earth and other compatible programs	
maps_pdf_format:    Printable maps in pdf format	
maps_prn_format:    Printable maps in HPGL2 printer file format with extension .prn	
maps_ps_format:    Print format maps in ps (postscript) format	
vector_data:    Line path, data contours, and survey boundary in ESRI shapefile (SHP) format, ESRI Geodatabase format, and/or AutoCAD dxf format
  1. How might this data set be cited?
    Burns, L.E., Fugro Airborne Surveys Corp., Stevens Exploration Management Corp., and Graham, G.R.C., 2015, Petersville mining district electromagnetic and magnetic airborne geophysical survey data compilation: Geophysical Report GPR 2015-3, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -151.675507
    East_Bounding_Coordinate: -150.603054
    North_Bounding_Coordinate: 62.651281
    South_Bounding_Coordinate: 62.297971
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 1996
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: digital, data
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a raster data set.
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 5
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -153
      Latitude_of_Projection_Origin: 0
      False_Easting: 500000.000000
      False_Northing: 0
      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest .00000001
      Ordinates (y-coordinates) are specified to the nearest .00000001
      Planar coordinates are specified in Meters
      The horizontal datum used is NAD27.
      The ellipsoid used is Clarke 1866.
      The semi-major axis of the ellipsoid used is 6378206.40000000037.
      The flattening of the ellipsoid used is 1/294.978698199999997.
  7. How does the data set describe geographic features?
    ascii_data
    ASCII format line data, other ASCII data (Source: Fugro Airborne Surveys Corp. and Stevens Exploration Management Corp.)
    databases_geosoft
    Geosoft format database of line data, other Geosoft format databases (Source: Fugro Airborne Surveys Corp. and Stevens Exploration Management Corp.)
    documents
    Project and field reports, survey background information, gridded data explanations, other supporting documentation (Source: Fugro Airborne Surveys Corp. and Stevens Exploration Management Corp. and Alaska Division of Geological & Geophysical Surveys (DGGS))
    grids_ermapper
    Geographically registered gridded data, ER Mapper ERS format (Source: Fugro Airborne Surveys Corp. and Stevens Exploration Management Corp. and Alaska Division of Geological & Geophysical Surveys (DGGS))
    grids_geosoft
    Geosoft-format binary grids, these grids can be viewed in ESRI ArcMap using a free plugin from Geosoft or using the free viewer available from Geosoft (Source: Fugro Airborne Surveys Corp. and Stevens Exploration Management Corp. and Alaska Division of Geological & Geophysical Surveys (DGGS))
    images_registered
    GeoTiff format images of all gridded data (Source: Alaska Division of Geological & Geophysical Surveys (DGGS))
    kmz
    Keyhole markup language (kml) kmz archive files of project data. Viewable in Google Earth and other compatible programs (Source: Alaska Division of Geological & Geophysical Surveys (DGGS))
    maps_pdf_format
    Printable maps in pdf format (Source: Fugro Airborne Surveys Corp. and Stevens Exploration Management Corp.)
    maps_prn_format
    Printable maps in HPGL2 printer file format with extension .prn (Source: Fugro Airborne Surveys Corp. and Stevens Exploration Management Corp.)
    maps_ps_format
    Print format maps in ps (postscript) format (Source: Fugro Airborne Surveys Corp. and Stevens Exploration Management Corp.)
    vector_data
    Line path, data contours, and survey boundary in ESRI shapefile (SHP) format, ESRI Geodatabase format, and/or AutoCAD dxf format (Source: Alaska Division of Geological & Geophysical Surveys (DGGS))

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
  2. Who also contributed to the data set?
    Funding was provided by the Alaska State Legislature.
  3. To whom should users address questions about the data?
    Alaska Division of Geological & Geophysical Surveys
    Metadata Manager
    3354 College Road
    Fairbanks, AK
    USA

    (907)451-5020 (voice)
    (907)451-5050 (FAX)
    dggspubs@alaska.gov
    Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays
    Contact_Instructions:
    Please view our website (https://www.dggs.alaska.gov) for the latest information on available data. Please contact us using the e-mail address provided above when possible.

Why was the data set created?

The Petersville survey covers the southwestern mineral belt referred to by Hawley and Clark (1973) as the Chulitna-Yentna mineral belt. The belt is about 160 km long and occurs about 200 km north of Anchorage near the Parks Highway. These data were recorded to assist and promote mineral exoplortion in the reqion and to aid geologic mapping of the region.

How was the data set created?

  1. From what previous works were the data drawn?
    Akima, H., 1970 (source 1 of 24)
    Akima, H., 1970, A new method of interpolation and smooth curve fitting based on local procedures: Journal of the Association of Computing Machinery v. 7, no. 4, Association for Computing Machinery, New York, NY, USA.

    Type_of_Source_Media: paper
    Source_Contribution: total magnetic field data
    Fraser, D.C., 1978 (source 2 of 24)
    Fraser, D.C., 1978, Resistivity mapping with an airborne multicoil electromagnetic system: Geophysics v. 43, Society of Exploration Geophysicists, Tulsa, OK, United States.

    Type_of_Source_Media: paper
    Source_Contribution: raw and processed point data along flight lines
    Burns, L.E., 1997 (source 3 of 24)
    Burns, L.E., 1997, Portfolio of aeromagnetic and resistivity maps of the Petersville mining district, Alaska: Public Data File PDF 97-15, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 13 p
    Type_of_Source_Media: paper
    Source_Contribution: legacy data compilation
    Burns, L.E. and others, 2005, 0 p. (source 4 of 24)
    Burns, L.E., Fugro Airborne Surveys Corp., and Stevens Exploration Management Corp., 2005, 7200 Hz coplanar apparent resistivity of the Petersville mining district, Alaska: Geophysical Report GPR 2004-9-2A, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:63,360
    Type_of_Source_Media: paper
    Source_Scale_Denominator: 63360
    Source_Contribution: legacy data compilation
    Burns, L.E. and others, 2005, 0 p. (source 5 of 24)
    Burns, L.E., Fugro Airborne Surveys Corp., and Stevens Exploration Management Corp., 2005, 7200 Hz coplanar apparent resistivity of the Petersville mining district, Alaska: Geophysical Report GPR 2004-9-2B, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:63,360
    Type_of_Source_Media: paper
    Source_Scale_Denominator: 63360
    Source_Contribution: legacy data compilation
    Burns, L.E. and others, 2005, 0 p. (source 6 of 24)
    Burns, L.E., Fugro Airborne Surveys Corp., and Stevens Exploration Management Corp., 2005, 900 Hz coplanar apparent resistivity of the Petersville mining district, Alaska: Geophysical Report GPR 2004-9-3A, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:63,360
    Type_of_Source_Media: paper
    Source_Scale_Denominator: 63360
    Source_Contribution: legacy data compilation
    Burns, L.E. and others, 2005, 0 p. (source 7 of 24)
    Burns, L.E., Fugro Airborne Surveys Corp., and Stevens Exploration Management Corp., 2005, 900 Hz coplanar apparent resistivity of the Petersville mining district, Alaska: Geophysical Report GPR 2004-9-3B, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:63,360
    Type_of_Source_Media: paper
    Source_Scale_Denominator: 63360
    Source_Contribution: legacy data compilation
    Burns, L.E. and others, 2005 (source 8 of 24)
    Burns, L.E., Fugro Airborne Surveys Corp., and Stevens Exploration Management Corp., 2005, Line, gridded, and vector data, and selected plot files of the Petersville mining district, Alaska: Geophysical Report GPR 2004-9, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 DVD
    Type_of_Source_Media: paper
    Source_Contribution: legacy data compilation
    Burns, L.E. and others, 2005, 0 p. (source 9 of 24)
    Burns, L.E., Fugro Airborne Surveys Corp., and Stevens Exploration Management Corp., 2005, Total magnetic field of the Petersville mining district, Alaska: Geophysical Report GPR 2004-9-1A, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:63,360
    Type_of_Source_Media: paper
    Source_Scale_Denominator: 63360
    Source_Contribution: legacy data compilation
    Burns, L.E. and others, 2005, 0 p. (source 10 of 24)
    Burns, L.E., Fugro Airborne Surveys Corp., and Stevens Exploration Management Corp., 2005, Total magnetic field of the Petersville mining district: Geophysical Report GPR 2004-9-1B, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:63,360
    Type_of_Source_Media: paper
    Source_Scale_Denominator: 63360
    Source_Contribution: legacy data compilation
    DGGS Staff and others, 1997 (source 11 of 24)
    Staff, DGGS, Dighem, and WGM, Inc., 1997, 7200 Hz resistivity contours of the Petersville mining district, Alaska: Public Data File PDF 97-12, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:63,360
    Type_of_Source_Media: paper
    Source_Scale_Denominator: 63360
    Source_Contribution: legacy data compilation
    DGGS Staff and others, 1997 (source 12 of 24)
    Staff, DGGS, Dighem, and WGM, Inc., 1997, 7200 Hz resistivity contours of the Petersville mining district, Alaska: Report of Investigation RI 97-8, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:63,360
    Type_of_Source_Media: paper
    Source_Scale_Denominator: 63360
    Source_Contribution: legacy data compilation
    DGGS Staff and others, 1997 (source 13 of 24)
    Staff, DGGS, Dighem, and WGM, Inc., 1997, 900 Hz resistivity contours of the Petersville mining district, Alaska: Public Data File PDF 97-11, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:63,360
    Type_of_Source_Media: paper
    Source_Scale_Denominator: 63360
    Source_Contribution: legacy data compilation
    DGGS Staff and others, 1997 (source 14 of 24)
    Staff, DGGS, Dighem, and WGM, Inc., 1997, 900 Hz resistivity contours of the Petersville mining district, Alaska: Report of Investigation RI 97-7, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:63,360
    Type_of_Source_Media: paper
    Source_Scale_Denominator: 63360
    Source_Contribution: legacy data compilation
    DGGS Staff and others, 1997 (source 15 of 24)
    Staff, DGGS, Dighem, and WGM, Inc., 1997, CD-ROM digital archive files of 1996 survey data for Chulitna and Petersville mining districts, Alaska: Public Data File PDF 97-5, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 DVD
    Type_of_Source_Media: CD-ROM
    Source_Contribution: legacy data compilation
    DGGS Staff and others, 1997 (source 16 of 24)
    Staff, DGGS, Dighem, and WGM, Inc., 1997, Diazo film version of RI 97-5: Total field magnetics and electromagnetic anomalies of the Petersville mining district, Alaska: Public Data File PDF 97-10, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:63,360
    Type_of_Source_Media: paper
    Source_Scale_Denominator: 63360
    Source_Contribution: legacy data compilation
    DGGS Staff and others, 1997 (source 17 of 24)
    Staff, DGGS, Dighem, and WGM, Inc., 1997, Disk containing gridded files and section lines of the 1996 geophysical survey data for Petersville mining district: Public Data File PDF 97-14, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 DVD
    Type_of_Source_Media: paper
    Source_Contribution: legacy data compilation
    DGGS Staff and others, 1997 (source 18 of 24)
    Staff, DGGS, Dighem, and WGM, Inc., 1997, Flight line maps of the Petersville mining district, Alaska: Public Data File PDF 97-9, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:63,360
    Type_of_Source_Media: paper
    Source_Scale_Denominator: 63360
    Source_Contribution: legacy data compilation
    DGGS Staff and others, 1997 (source 19 of 24)
    Staff, DGGS, Dighem, and WGM, Inc., 1997, Total field magnetics and detailed electromagnetic anomalies of the northeast Petersville mining district, Alaska: Public Data File PDF 97-13B, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:31,680
    Type_of_Source_Media: paper
    Source_Scale_Denominator: 31680
    Source_Contribution: legacy data compilation
    DGGS Staff and others, 1997 (source 20 of 24)
    Staff, DGGS, Dighem, and WGM, Inc., 1997, Total field magnetics and detailed electromagnetic anomalies of the southeast Petersville mining district, Alaska: Public Data File PDF 97-13C, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:31,680
    Type_of_Source_Media: paper
    Source_Scale_Denominator: 31680
    Source_Contribution: legacy data compilation
    DGGS Staff and others, 1997 (source 21 of 24)
    Staff, DGGS, Dighem, and WGM, Inc., 1997, Total field magnetics and detailed electromagnetic anomalies of the southwest Petersville mining district, Alaska: Public Data File PDF 97-13A, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:31,680
    Type_of_Source_Media: paper
    Source_Scale_Denominator: 31680
    Source_Contribution: legacy data compilation
    DGGS Staff and others, 1997 (source 22 of 24)
    Staff, DGGS, Dighem, and WGM, Inc., 1997, Total field magnetics and electromagnetic anomalies of the Petersville mining district, Alaska: Report of Investigation RI 97-5, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:63,360
    Type_of_Source_Media: paper
    Source_Scale_Denominator: 63360
    Source_Contribution: legacy data compilation
    DGGS Staff and others, 1997 (source 23 of 24)
    Staff, DGGS, Dighem, and WGM, Inc., 1997, Total field magnetics of the Petersville mining district, Alaska: Report of Investigation RI 97-6, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:63,360
    Type_of_Source_Media: paper
    Source_Scale_Denominator: 63360
    Source_Contribution: legacy data compilation
    Pritchard, R.A. and Dighem, 1997 (source 24 of 24)
    Pritchard, R.A., and Dighem, 1997, Project report of the airborne geophysical survey for the Chulitna and Petersville mining districts: Public Data File PDF 97-8, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 293 p., 2 sheets, scale 1:63,360
    Type_of_Source_Media: paper
    Source_Scale_Denominator: 63360
    Source_Contribution: legacy data compilation
  2. How were the data generated, processed, and modified?
    Date: 1996 (process 1 of 11)
    Geophysical data - Geophysical data - The airborne geophysical data was acquired with a DIGHEM-V Electromagnetic (EM) system and a Scintrex cesium magnetometer towed at nominal survey altitudes of 30 meters (~100 ft) and 20 meters (~65 ft) respectively. The survey also recorded data from a radar altimeter, GPS navigation system, 50/60 Hz monitors and video camera. Flights were performed with an AS350B-1 Squirrel helicopter at a mean terrain clearance of 200 feet and an average airspeed for the Petersville survey of 68 mph (109 km/h). The flight direction was E-W for the Petersville survey. All survey flight lines were spaced at one-quarter mile. Tie lines were flown perpendicular to the flight lines at intervals of approximately 3 miles. A Sercel NR106 NAVSTAR (RT-DGPS) Global Positioning System was used for both navigation and flight path recovery. The helicopter position was derived every 0.5 seconds using post-flight differential positioning to a relative accuracy of better than 5 m. (Maps produced during 2004 incorrectly state 10 m, and is considered to be a minor error.) Flight path positions were projected onto the Clarke 1866 (UTM zone 5) spheroid, 1927 North American datum using a central meridian (CM) of 153 degrees, a north constant of 0 and an east constant of 500,000. Positional accuracy of the presented data is better than 10 m with respect to the UTM grid.
    Date: 1996 (process 2 of 11)
    Total magnetic field data - The total magnetic field data were acquired with a sampling interval of 0.1 seconds, and were (1) corrected for diurnal variations by subtraction of the digitally recorded base station magnetic data, (2) leveled to the tie line data, and (3) interpolated onto a regular 100 m grid using a modified Akima (1970) technique. The regional variation (or IGRF gradient, 1985, updated to October, 1996) was removed from the leveled magnetic data for the Petersville survey. The aeromagnetic data were interpolated onto a regular 100 m grid using a modified Akima (1970) technique. The magnetic base station was a GSM-19T digital recording proton precession machine with a sensitivity of 0.20 nT and was sampled once every 3 seconds. Data sources used in this process:
    • Akima, H., 1970
    Date: 1996 (process 3 of 11)
    Inphase and quadrature components - The DIGHEM-V EM system measured inphase and quadrature components at five frequencies. Two vertical coaxial-coil pairs operated at 898 (900) and 6491 (5,500) Hz while three horizontal coplanar-coil pairs operated at 1049 for flights 30-58 and 1010 for flights 60-67 (900), 7216 (7200), and 56,598 (56 000) Hz. EM data were sampled at 0.1 second intervals. The EM inphase and quadrature data were drift corrected using base level data collected at high altitude (areas of no signal). Along-line filters were applied to the data to remove spheric spikes. The data were inspected for variations in phase, and a phase correction was applied to the data if necessary. Resistivities were then calculated from the inphase and quadrature data for all frequencies based on a pseudo-layer half-space model. Manual leveling of the inphase and quadrature of each coil pair, based on the resistivity data and comparisons to the data from the other frequencies, was performed. Automated micro-leveling was carried out in areas of low signal. The resistivity data were then interpolated onto a regular 100 m grid using a modified Akima (1970) technique. The resulting grids are subjected to a 3x3 hanning filter before contouring and map production. The EM system responds to bedrock conductors, conductive overburden, and cultural sources. The power line monitors and the flight track video were examined to locate cultural sources. The EM anomalies that are indicated are classified by conductance.
    Date: 2004 (process 4 of 11)
    Geographically registered gridded data - The binary databases originally created for the 1994 project have been taken from the Fugro Airborne Surveys Archive and converted to Geosoft ASCII format. All data channels are now represented in real world units without the presence of multipliers. No reprocessing of data has been carried out. The data are presented in a modern, updated format. Gridded data of the total magnetic field, and 900 Hz and 7200 Hz coplanar resistivities were converted from 100 m cells as originally provided to 25 m cells and are provided in ER Mapper and Geosoft binary grid formats. Various vector files were either remade or converted from other formats to Autocad dxf format, version 13. The data contour vector files were recreated for the new grids. The original files containing the flight lines, interpretation overlays (associated with DGGS Public-data File 97-8), and the electromagnetic anomaly symbols [included on DGGS PDF 97-13A, PDF 97-13B, and PDF 97-13C] were converted to the Autocad format as part of this project.
    Date: 2005 (process 5 of 11)
    Print files - Plot files of the maps were produced by Fugro in HPGL2, postscript, and Adobe Acrobat formats. The HPGL2 files were produced by Hewlett Packard DesignJet 5500 HPGL/2 driver version 5.32 and will not work with all plotters, but do plot on the DGGS HP DesignJet 5000. The postscript files were produced by Hewlett Packard DesignJet 5000 Postscript 3 V4.28 and should work with all HP plotters that can read Postscript 3. The HPGL2 files have brighter colors and sharper topography than the postscript files.
    Date: 2015 (process 6 of 11)
    Legacy data compilation - DGGS staff compiled and organized previously published data and the originating data from the contractor. DGGS staff converted select hpp files into PDFs to complete the PDF map collection. Original vector data were compiled into an ESRI ArcMap File Geodatabase using ArcMap 10.2.2's CAD to Geodatabase tool in batch mode. In this publication's older products and documentation the magnetic data products have been referred to as Total Field Magnetics on the maps and the MAGIGRF channel in the line data and 'tfm' as a filename abbreviation. The new term 'sim_magtf' has been created to rename and clarify that the data are not representative of the true total magnetic field as the IGRF values have been removed with a single average IGRF value added back to the data, resulting in the IGRF gradient being removed. The term simulated magnetic total field and the filename abbreviation 'sim_magtf' is now used to identify the final magnetic data. Data sources used in this process:
    • Burns, L.E., 1997
    • Burns, L.E. and others, 2005, 0 p.
    • Burns, L.E. and others, 2005, 0 p.
    • Burns, L.E. and others, 2005, 0 p.
    • Burns, L.E. and others, 2005, 0 p.
    • Burns, L.E. and others, 2005
    • Burns, L.E. and others, 2005, 0 p.
    • Burns, L.E. and others, 2005, 0 p.
    • DGGS Staff and others, 1997
    • DGGS Staff and others, 1997
    • DGGS Staff and others, 1997
    • DGGS Staff and others, 1997
    • DGGS Staff and others, 1997
    • DGGS Staff and others, 1997
    • DGGS Staff and others, 1997
    • DGGS Staff and others, 1997
    • DGGS Staff and others, 1997
    • DGGS Staff and others, 1997
    • DGGS Staff and others, 1997
    • DGGS Staff and others, 1997
    • DGGS Staff and others, 1997
    • Pritchard, R.A. and Dighem, 1997
    Date: 2015 (process 7 of 11)
    Data in Geosoft GDB format - These data were created by importing the final ascii data into Geosoft Oasis Montaj v8.3 using the provided *.iO import file.
    Date: 2015 (process 8 of 11)
    Geographically registered gridded data in Geosoft GRD format - Geographically registered gridded data in Geosft GRD format - These data were created by DGGS using the final ascii data. Geosft Oasis montaj v8.2 was used to create the grid files. 80 meter grid cell size and the minimum curvature operate were used in the production of these grids. The analytic signal and first vertical derivative grids are smoothed using a 9x9 convolution filter.
    Date: 2015 (process 9 of 11)
    Geographically registered gridded data in GeoTiff format - These data were created by DGGS using Geosft Oasis montaj v8.2. Geosoft grd files were displayed in Geosft and exported to GeoTiff. A matching colorbar for each grid was displayed in Geosoft and export as a GeoTiff.
    Date: 2015 (process 10 of 11)
    Google Earth KMZ files - Created Google Earth KMZ files from the GeoTiff format gridded data using ESRI ArcMap 10.2.2.
    Date: 2015 (process 11 of 11)
    Boundary polygon - The boundary polygon was generated by loading the final line data in Geosoft Oasis montaj v8.3. The final magnetic data was gridded using the Minimum Curvature option with the following settings: grid cell size = 1/5 of line spacing, blanking distance = double the line spacing, cells to extend beyond data = 0. The polygon file was created using Grid Outline tool with edge resolution = 1. The polygon file was exported to ESRI shapefile.
  3. What similar or related data should the user be aware of?

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
    Geophysical data were acquired according to the contractor, contract, and request-for-proposals specifications. For additional detail about survey parameters, see the accompanying project report available in the documents directory of this data distribution package.
  2. How accurate are the geographic locations?
    Station coordinates were positioned using a real-time or post-processed corrected differential GPS.
  3. How accurate are the heights or depths?
    Not applicable
  4. Where are the gaps in the data? What is missing?
    This data set includes files that contain processed aeromagnetic measurements, electromagnetic measurements, altimetry measurements, and locational data for the entire survey area.
  5. How consistent are the relationships among the observations, including topology?
    Data originate from one company using the same contract specifications for all data. The originating coordinate system was retained for all publication products.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints:
This report, map, and/or dataset is available directly from the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys (see contact information below).
Use_Constraints:
Any hard copies or published datasets utilizing these datasets shall clearly indicate their source. If the user has modified the data in any way, the user is obligated to describe the types of modifications the user has made. The user specifically agrees not to misrepresent these datasets, nor to imply that changes made by the user were approved by the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys. The State of Alaska makes no express or implied warranties (including warranties for merchantability and fitness) with respect to the character, functions, or capabilities of the electronic data or products or their appropriateness for any user's purposes. In no event will the State of Alaska be liable for any incidental, indirect, special, consequential, or other damages suffered by the user or any other person or entity whether from the use of the electronic services or products or any failure thereof or otherwise. In no event will the State of Alaska's liability to the Requestor or anyone else exceed the fee paid for the electronic service or product.
  1. Who distributes the data set? (Distributor 1 of 1)
    Alaska Division of Geological & Geophysical Surveys
    Metadata Manager
    3354 College Road
    Fairbanks, AK
    USA

    (907)451-5020 (voice)
    (907)451-5050 (FAX)
    dggspubs@alaska.gov
    Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays
    Contact_Instructions:
    Please view our website (https://www.dggs.alaska.gov) for the latest information on available data. Please contact us using the e-mail address provided above when possible.
  2. What's the catalog number I need to order this data set? GPR 2015-3
  3. What legal disclaimers am I supposed to read?
    The State of Alaska makes no expressed or implied warranties (including warranties for merchantability and fitness) with respect to the character, functions, or capabilities of the electronic data or products or their appropriateness for any user's purposes. In no event will the State of Alaska be liable for any incidental, indirect, special, consequential, or other damages suffered by the user or any other person or entity whether from the use of the electronic services or products or any failure thereof or otherwise. In no event will the State of Alaska's liability to the Requestor or anyone else exceed the fee paid for the electronic service or product.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 25-Sep-2021
Metadata author:
Alaska Division of Geological & Geophysical Surveys
Attn: Simone Montayne
Metadata Manager
3354 College Road
Fairbanks, AK
USA

(907)451-5020 (voice)
(907)451-5050 (FAX)
dggspubs@alaska.gov
Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays
Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
Metadata extensions used:

Generated by mp version 2.9.50 on Fri Sep 24 16:26:35 2021