Alaska Highway corridor electromagnetic and magnetic airborne geophysical survey data compilation

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Frequently anticipated questions:


What does this data set describe?

Title:
Alaska Highway corridor electromagnetic and magnetic airborne geophysical survey data compilation
Abstract:
The Alaska Highway corridor electromagnetic and magnetic airborne geophysical survey is located in interior Alaska along the Alaska Highway corridor, from Delta Junction to the Canadian border. Frequency domain electromagnetic and magnetic data were collected with the RESOLVE system from August 27th, 2005 to January 16th, 2006. A total of 22,948.5 line kilometers were collected covering 8117.5 square kilometers. Line spacing was 400 meters (m). The data, as well as additional metadata, are available from the DGGS website: <http://doi.org/10.14509/30462>.
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 HPGL/G printer file format with extension .prn 
profiles_stacked:    Distance-based profiles of the digitally recorded geophysical data are generated and plotted at an appropriate scale. The profiles display electromagnetic anomalies with their respective interpretive symbols	
resistivity_models:    ACSII CSV format resistivity models in project coordinates with data field guides, figures and supporting documentation in ASCII text, PDF, KML, and/or other formats.	
vector_data:    Line path, data contours, and survey boundary in ESRI shapefile (SHP) format, ESRI Geodatabase format, and/or AutoCAD dxf format
  1. How should this data set be cited?

    Burns, L.E., Graham, G.E., Emond, A.M., Stevens Exploration Management Corp., and Surveys, Fugro Airborne, 2020, Alaska Highway corridor electromagnetic and magnetic airborne geophysical survey data compilation: Geophysical Report GPR 2020-15, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 17 p.

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -145.897848
    East_Bounding_Coordinate: -140.851779
    North_Bounding_Coordinate: 64.235769
    South_Bounding_Coordinate: 62.396392

  3. What does it look like?

  4. Does the data set describe conditions during a particular time period?

    Calendar_Date: 2006
    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?

    2. What coordinate system is used to represent geographic features?

      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 7
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -141
      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 North American Datum of 1927.
      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: Stevens Exploration Management Corp. and Fugro Airborne Surveys)

    databases_geosoft
    Geosoft format database of line data, other Geosoft format databases (Source: Stevens Exploration Management Corp. and Fugro Airborne Surveys)

    documents
    Project and field reports, survey background information, gridded data explanations, other supporting documentation (Source: Stevens Exploration Management Corp. and Fugro Airborne Surveys and Alaska Division of Geological & Geophysical Surveys (DGGS))

    grids_ermapper
    Geographically registered gridded data, ER Mapper ERS format (Source: Stevens Exploration Management Corp. and Fugro Airborne Surveys 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: Stevens Exploration Management Corp. and Fugro Airborne Surveys 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: Stevens Exploration Management Corp. and Fugro Airborne Surveys)

    maps_prn_format
    Printable maps in pdf format (Source: Print format maps in HPGL/G printer file format with extension .prn)

    profiles_stacked
    Distance-based profiles of the digitally recorded geophysical data are generated and plotted at an appropriate scale. The profiles display electromagnetic anomalies with their respective interpretive symbols (Source: Stevens Exploration Management Corp. and Fugro Airborne Surveys)

    resistivity_models
    ACSII CSV format resistivity models in project coordinates with data field guides, figures and supporting documentation in ASCII text, PDF, KML, and/or other formats. (Source: Stevens Exploration Management Corp. and Fugro Airborne Surveys)

    vector_data
    Line path, data contours, and survey boundary in ESRI shapefile (SHP) format, ESRI Geodatabase format, and/or AutoCAD dxf format (Source: Stevens Exploration Management Corp. and Fugro Airborne Surveys and 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 99709-3707
    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


Why was the data set created?

This airborne geophysical survey was acquired to gather geologic information to assess the geologic hazards, construction materials, and mineral potential on the Alaska Highway corridor in east-central Alaska. The geophysical information acquired helps provide information on conductive overburden, potential construction materials, permafrost, fractures and faulting, and other information. Prospects within the survey area include Road Metal, Triple Z (ASARCO), and Discovery Zone. In addition, these data are to assist geologic mapping in the region.


How was the data set created?

  1. From what previous works were the data drawn?

    Burns, L.E. and others, 2006 (source 1 of 2)
    Burns, L.E., Fugro Airborne Surveys Corp., and Stevens Exploration Management Corp., 2006, Line, grid, and vector data, and plot files for the airborne geophysical survey of the Alaska Highway corridor, east-central Alaska: Geophysical Report GPR 2006-6, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 DVD
    Type_of_Source_Media: paper
    Source_Contribution: Data collection, processing, and delivery

    Burns, L.E. and others, 2008 (source 2 of 2)
    Burns, L.E., Fugro Airborne Surveys Corp., and Stevens Exploration Management Corp., 2008, Final processed database for the airborne geophysical surveys of the Alaska Highway corridor, east-central Alaska: Geophysical Report GPR 2006-8, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 DVD
    Type_of_Source_Media: paper
    Source_Contribution: Data collection, processing, and delivery

  2. How were the data generated, processed, and modified?

    Date: 2006 (process 1 of 9)
    Data collection, processing, and delivery - The airborne geophysical data were acquired under contract with Stevens Exploration Management Corp. Airborne geophysical data for the area were acquired and processed by Fugro Airborne Surveys. The contractor's project report and other supporting documents are in the "documents" digital data package. They provide detailed documentation of the system specifications, data collection, processing, and delivery.

    Data sources used in this process:

    • Burns, L.E. and others, 2006
    • Burns, L.E. and others, 2008

    Date: 2019 (process 2 of 9)
    Grid development - The analytic signal grid was generated by using the analytic signal function in Geosoft Oasis Montaj v9 on. The derivatives in the analytic signal calculation were computed using a fast Fourier transform (FFT) based 2D filter.

    Date: 2019 (process 3 of 9)
    RGB GeoTiff creation - RGB GeoTIFF raster files of gridded data were exported using Geosoft v9 by loading each Geosoft grid onto a map and using the map export tool.

    Date: 2019 (process 4 of 9)
    GeoPDF creation - Geospatial pdf file created using the Export Map function in Geosoft Oasis Montaj v9 with all maps layers visible.

    Date: 2019 (process 5 of 9)
    DXF conversion and geographic referencing - Contractor provided AutoCAD DXF files were converted to an ESRI Geodatabase in ArcMap v10 using the CAD to Geodatabase tool.

    Date: 2019 (process 6 of 9)
    Standard Boundary Polygon - The boundary polygon was generated by loading the final line data in Geosoft Oasis montaj v9. The 8200 Hz apparent resistivity data was gridded using the Minimum Curvature option with the following settings: grid cell size = 25 m, blanking distance = 800 m, cells to extend beyond data = 2. The polygon was created and drawn on the map using Grid Outline tool with edge resolution = 0.2. The polygon was exported to ESRI shapefile.

    Date: 2019 (process 7 of 9)
    Keyhole markup language (kml) KMZ archive creation - Data were exported from Geosoft and ESRI ArcMap to kml format files and/or KMZ archives. These files were then combined and modified in Google Earth Pro to create the final KMZ file.

    Date: 2019 (process 8 of 9)
    Simulated Magnetic Total Field - 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 MAG channel in the line data and 'mag' 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 value added back to the entire dataset, resulting in the IGRF gradient being removed. The term simulated magnetic total field and the filename abbreviation 'sim_magtf' is now used to identify these magnetic data.

    Date: 2019 (process 9 of 9)
    Data cataloged for archival and publication - All files were renamed and placed in a standardized set of folders according to the DGGS Geophysics Data Management Manual. Where applicable and as needed data were converted to newer file formats and new files were created. Supporting documentation including but not limited to readme text files, maps, figures, survey overview report, missing data type explanations, and metadata were created.

  3. What similar or related data should the user be aware of?

    Staff, DGGS, 2014, Airborne GeophysWeb: A compilation of geophysical data from DGGS and cooperating agencies: Digital Data Series DDS 2, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Staff, DGGS, 2016, Alaska merged geophysical data grids: Digital Data Series DDS 12, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 3 p


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?

    These data are positioned with post-processed differential GPS. Discussion of grid resolution and factors that may impact the overall horizontal accuracy of the gridded data is available in the documents directory of this data distribution package.

  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 99709-3707
    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
  2. What's the catalog number I need to order this data set?

    GPR 2020-15

  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: 02-Jul-2020
Metadata author:
Alaska Division of Geological & Geophysical Surveys
Attn: Simone Montayne
Metadata Manager
3354 College Road
Fairbanks, AK 99709-3707
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:


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