Airborne magnetic geophysical survey of the Porcupine River area, Alaska

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Frequently anticipated questions:


What does this data set describe?

Title:
Airborne magnetic geophysical survey of the Porcupine River area, Alaska
Abstract:
The Porcupine River fixed wing aeromagnetic geophysical survey is located in eastern Alaska, along the Canadian border, in the Sheenjek and Black mining districts. This survey is located about 135 kilometers east of Fort Yukon, Alaska and about 85 kilometers east of Circle, Alaska. Magnetic data were collected with a Geometrics G-822A cesium-vapor split-beam sensor mounted in a tail stinger. Between May 5th and June 28th, 2017, a total of 50,329 line kilometers were collected covering 13,646.9 square kilometers. Data were collected at a line spacing of 300 meters (m) with a mean ground clearance of 235 m. The data, as well as additional metadata, are available from the DGGS website: <http://doi.org/10.14509/29737>.
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
vector_data:    Line path, data contours, and survey boundary in ESRI shapefile (SHP) format, ESRI Geodatabase format, and/or AutoCAD dxf format
video_flightpath:    Survey flight path downward-facing video
  1. How should this data set be cited?

    Emond, A.M., Graham, G.R.C., Drenth, B.J., Jones, J.V.III., and Inc., EON Geosciences, 2019, Airborne magnetic geophysical survey of the Porcupine River area, Alaska: Geophysical Report GPR 2019-1, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 10 p.

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -144.440992
    East_Bounding_Coordinate: -142.332874
    North_Bounding_Coordinate: 68.012429
    South_Bounding_Coordinate: 65.791948

  3. What does it look like?

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

    Calendar_Date: 2017
    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 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: EON Geosciences Inc.)

    databases_geosoft
    Geosoft format database of line data, other Geosoft format databases (Source: EON Geosciences Inc.)

    documents
    Project and field reports, survey background information, gridded data explanations, other supporting documentation (Source: EON Geosciences Inc. and Alaska Division of Geological & Geophysical Surveys (DGGS))

    grids_ermapper
    Geographically registered gridded data, ER Mapper ERS format (Source: EON Geosciences Inc. 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: EON Geosciences Inc. 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: EON Geosciences Inc.)

    vector_data
    Line path, data contours, and survey boundary in ESRI shapefile (SHP) format, ESRI Geodatabase format, and/or AutoCAD dxf format (Source: EON Geosciences Inc. and Alaska Division of Geological & Geophysical Surveys (DGGS))

    video_flightpath
    Survey flight path downward-facing video (Source: EON Geosciences Inc.)


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 U.S. Geological Surveys Mineral Resources Program. USGS grant: G16AC00169.

  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?

The survey data will be used by USGS, DGGS, and other researchers to better understand the crustal suture between Arctic Alaska and North America. Both the North American and Arctic Alaska successions contain rift- and arc-related volcanic and plutonic rocks associated with substantial mineral endowment farther west in the Brooks Range and to the east in the Selwyn Basin of Yukon Territory. The boundary of the two terranes is inferred to lie in a broad corridor parallel to the Porcupine River near where it crosses the international border. The data will also assist with evaluation of the mineral-resource potential for land management planning.


How was the data set created?

  1. From what previous works were the data drawn?

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

    Date: 2017 (process 1 of 5)
    Data collection, processing, and delivery - The airborne geophysical data were acquired under contract to EON geosciences, INC.. 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.

    Date: 2019 (process 2 of 5)
    Inferred the decimal precision - The inferred the decimal precision of the linedata (.csv, .gdb) was received from the contractor. DGGS staff added the inferred precision to the readme documentation and used that to create .io, .o0, and .i3 files to make .xyz format files.

    Date: 2019 (process 3 of 5)
    Standard Boundary Polygon - The final boundary polygon was generated by loading the line data in Geosoft Oasis Montaj v9. The channel MAG was gridded using the Minimum Curvature option with the following settings: grid cell size = 25, blanking distance = 800, cells to extend beyond data = 2. The polygon file was created using the Grid Outline tool with edge resolution = 1. The polygon file was exported to ESRI shapefile.

    Date: 2019 (process 4 of 5)
    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 5 of 5)
    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: 1 DVD


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. 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 2019-1

  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: 12-Jun-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:


Generated by mp version 2.9.21 on Fri Jun 14 12:34:20 2019