Icy Cape airborne magnetic geophysical survey, southeast Alaska

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Frequently anticipated questions:


What does this data set describe?

Title: Icy Cape airborne magnetic geophysical survey, southeast Alaska
Abstract:
The Icy Cape airborne magnetic geophysical survey covers parts of Icy Cape, Alaska, which is located on the coast of the Gulf of Alaska near Icy Bay. Data were acquired by helicopter between August 20th and August 22nd, 2016, by Precision GeoSurveys Inc. The survey helicopter was equipped with a Scintrex cesium vapor CS-3 magnetometer, spectrometer, data acquisition system, magnetic compensation system, pilot guidance unit (PGU), and GPS navigation system. A Garmin VIRB XE video camera integrated with a GPS antenna was used to record the flight path video. In addition, two GEM GSM-19T magnetometer base stations with integrated GPS time synchronization were used to record diurnal magnetic variations. The survey area consists of four contiguous blocks covering an irregular area of 42.5 km by 19.1 km with 173 survey lines and 16 tie lines. The four blocks are centered 130 km northwest of Yakutat, Alaska, and cover a total of 520.8 square km. A total of 846.2 line-km were collected. The data, as well as additional metadata, are available from the DGGS website: http://doi.org/10.14509/29742.
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 might this data set be cited?
    Emond, A.M., Graham, G.R.C., Eden, Karsten, and Inc., Precision GeoServices, 2021, Icy Cape airborne magnetic geophysical survey, southeast Alaska: Geophysical Report GPR 2021-1, 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: -142.266316
    East_Bounding_Coordinate: -141.490370
    North_Bounding_Coordinate: 60.063901
    South_Bounding_Coordinate: 59.886432
  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?
      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: 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 WGS84.
      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: Precision GeoSurveys Inc.)
    databases_geosoft
    Geosoft format database of line data, other Geosoft format databases (Source: Precision GeoSurveys Inc.)
    documents
    Project and field reports, survey background information, gridded data explanations, other supporting documentation (Source: Precision GeoSurveys Inc. and Alaska Division of Geological & Geophysical Surveys (DGGS))
    grids_ermapper
    Geographically registered gridded data, ER Mapper ERS format (Source: Precision GeoSurveys 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: Precision GeoSurveys 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: Precision GeoSurveys Inc.)
    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))
    video_flightpath
    Survey flight path downward-facing video (Source: Precision GeoSurveys 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 State of Alaska, Mental Health Trust Land Office.
  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?

This airborne magnetic survey was performed to evaluate and promote State of Alaska, Mental Health Trust owned lands in the Icy Cape area for accumulations of concentrated heavy mineral sands.

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: 2016 (process 1 of 5)
    Data collection, processing, and delivery - The airborne geophysical data were acquired under contract with Precision GeoSurveys Inc. Airborne geophysical data for the area were acquired and processed by Precision GeoSurveys 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: 2020 (process 2 of 5)
    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: 2020 (process 3 of 5)
    ER Mapper grid creation - Data value ER Mapper ers format grids were created from the delivered Geosoft format grids using Geosoft Oasis montaj v9. The grid copy/convert tool was used.
    Date: 2020 (process 4 of 5)
    Merged Boundary Polygon - A merged and dissolved boundary polygon was created in ArcMap from the four polygons of each data block.
    Date: 2020 (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?

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 2021-1
  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: 07-Dec-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 Mon Dec 06 19:59:29 2021