Airborne electromagnetic and magnetic survey, Yukon Crossing, interior Alaska

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Frequently anticipated questions:


What does this data set describe?

Title:
Airborne electromagnetic and magnetic survey, Yukon Crossing, interior Alaska
Abstract:
The Alaska Division of Geological & Geophysical Surveys managed the collections of magnetic and frequency domain electromagnetic data to increase geologic understanding of the Yukon Crossing area surrounding mile 56 of the Dalton Highway, interior Alaska. The 162-square-kilometer survey was flown February 25th to March 1st, 2016. The data were collected by CGG using the RESOLVE airborne geophysical survey system with line spacing of: 400 meters (m), or 80 min a smaller area surrounding the Yukon River, and three custom lines along theY ukon River. The data were measured 30 m above the ground surface using 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/10.14509/29682>.
Supplemental_Information:
ascii_data:    ASCII format line data, other ASCII data	
databases_geosoft:    Geosoft format database of final line data, other Geosoft format databases	
documents:    Project and field reports, survey background information, gridded data explanations, other 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	
images_registered:    GeoTiff format images of all gridded data	
kmz:    kml language kmz archive files of several project data types including resistivity model depth slices	
maps_pdf_format:    Printable maps in pdf format	
maps_prn_format:    Printable maps in HPGL/G printer file format with extension .prn	
photos_flightpath:    Survey flight path downward facing photos with GPS location in exif data	
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	
video_flightpath:    Survey flight path downward-facing video
  1. How should this data set be cited?

    Emond, A.M., Little, L.M., Graham, G.R.C., Minsley, B.J., and CGG, 2018, Airborne electromagnetic and magnetic survey, Yukon Crossing, interior Alaska: Geophysical Report GPR 2016-4, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 3 p.

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -149.891330
    East_Bounding_Coordinate: -149.560862
    North_Bounding_Coordinate: 65.933714
    South_Bounding_Coordinate: 65.819074

  3. What does it look like?

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

    Calendar_Date: 2016
    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: 6
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -147
      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 World Geodetic System of 1984.
      The ellipsoid used is WGS 84.
      The semi-major axis of the ellipsoid used is 6378137.
      The flattening of the ellipsoid used is 1/298.257223563000025.

  7. How does the data set describe geographic features?

    ascii_data
    ASCII format line data, other ASCII data (Source: CGG Canada Services Ltd.)

    databases_geosoft
    Geosoft format database of final line data, other Geosoft format databases (Source: CGG Canada Services Ltd.)

    documents
    Project and field reports, survey background information, gridded data explanations, other documentation (Source: CGG Canada Services Ltd.)

    grids_ermapper
    Geographically registered gridded data, ER Mapper ERS format (Source: 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 (Source: 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
    kml language kmz archive files of several project data types including resistivity model depth slices (Source: Alaska Division of Geological & Geophysical Surveys (DGGS))

    maps_pdf_format
    Printable maps in pdf format (Source: CGG Canada Services Ltd.)

    maps_prn_format
    Printable maps in HPGL/G printer file format with extension .prn (Source: CGG Canada Services Ltd.)

    photos_flightpath
    Survey flight path downward facing photos with GPS location in exif data (Source: Alaska Division of Geological & Geophysical Surveys (DGGS))

    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: Alaska Division of Geological & Geophysical Surveys (DGGS))

    vector_data
    Line path, data contours, and survey boundary in ESRI shapefile (SHP) format (Source: Alaska Division of Geological & Geophysical Surveys (DGGS), Fugro Airborne Surveys Corp. and Stevens Exploration Management Corp.)

    video_flightpath
    Survey flight path downward-facing video (Source: CGG Canada Services Ltd.)


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?

    The survey was funded by the Alaska Department of Transportation & Public Facilities as part of U.S. Department of Transportation Federal Highway Administration Project 0653(8), State Project NFHWY00010.

  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?

These geophysical data were collected for the Alaska Department of Transportation & Public Facilities to increase the geologic understanding of the Yukon Crossing area. The Dalton Highway and the Trans Alaska Pipeline cross the Yukon River at Yukon Crossing. Improving understanding of this area allows for informed infrastructure management and development.


How was the data set created?

  1. From what previous works were the data drawn?

    Akima, H., 1970 (source 1 of 1)
    Akima, H., 1970, A new method of interpolation and smooth curve fitting based on local procedures: null v. 7, no. 4, Association for Computing Machinery, New York, NY, USA.

    Online Links:

    • null

    Type_of_Source_Media: paper
    Source_Contribution: Data collection, processing, and delivery

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

    Date: 2016 (process 1 of 4)
    Data collection, processing, and delivery - The supporting documents in digital data package "documents" provides detailed process steps.

    Data sources used in this process:

    • Akima, H., 1970

    Date: 2016 (process 2 of 4)
    Resistivity modeling - Resistivity models were derived from the recorded electromagnetic data through a process called inversion. Inversion programs create a resistivity model that has a data signature nearly the same as the recorded data. When this occurs the model is said to "fit" the data. This process is non-unique, meaning that many different resistivity models could create similar data. The readme file in digital data package "resistivity_models" provides inversion-specific information.

    Date: 2017 (process 3 of 4)
    Boundary polygon - The boundary polygon was generated in Geosoft Oasis montaj v9 from the outer extents of the final line data. The final magnetic data were gridded using the Minimum Curvature option with the following settings: grid cell size = 1/5 of the maximum line spacing, blanking distance = double the maximum line spacing, cells to extend beyond data = 0. The polygon file was created using the Grid Outline tool with edge resolution = 1. The polygon file was exported to an ESRI shapefile.

    Date: 2018 (process 4 of 4)
    Resistivity Depth Slices Grids, Images, and KMZ - Resistivity models were gridded at specific depths below surface using Geosoft Oasis Montaj v9 to create Geosoft format grids. These depth slices were displayed with the same fixed-color scale by using a Geosoft *.zon file and exported to fixed color RGB GeoTiff images using Geosoft Oasis Montaj v9. The resulting GeoTiff images were imported into ArcMap v10. Using the "map to kml" tool in ArcMap v10 a keyhole markup language archive KMZ file was created making a GroundOverlay of each depth slice grid image. The KMZ was edited assigning a TimeSpan to each image where the 4-digit TimeSpan begin and end encompasses the depth below ground surface of the image. A resistivity colorbar was added to the KMZ as ScreenOverlay.

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

    Ball, L.B., Smith, B.D., Minsley, B.J., Abraham, J.D., Voss, C.I., Astley, B.N., Deszcz-Pan, Maria, and Cannia, J.C., 2014, Airborne electromagnetic and magnetic geophysical survey data of the Yukon Flats and Fort Wainwright areas, central Alaska, June 2010: Open-File Report OF 2011-1304, U.S. Geological Survey, United States.

    Online Links:

    Other_Citation_Details: 21 p
    Emond, A.M., Daanen, R.P., Graham, G.R.C., Walter Anthony, Katey, Liljedahl, A.K., Minsley, B.J., Barnes, D.L., Romanovsky, V.E., and Services, CGG Canada Ltd., 2018, Airborne electromagnetic and magnetic survey, Goldstream Creek watershed, interior Alaska: Geophysical Report GPR 2016-5, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 14 p
    Emond, A.M., Minsley, B.J., Daanen, R.P., Graham, G.R.C., and CGG, 2018, Airborne electromagnetic and magnetic survey, Western Yukon Flats, interior Alaska: Geophysical Report GPR 2016-2, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 3 p
    Graham, G.R.C., Emond, A.M., Daanen, R.P., Minsley, B.J., and CGG, 2018, Airborne electromagnetic and magnetic survey, Yukon Crossing to Fox profile, interior Alaska: Geophysical Report GPR 2016-3, 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 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.

  3. How accurate are the heights or depths?

    These data are positioned with post-processed differential GPS.

  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 2016-4

  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: 07-Jan-2019
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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