Aerorad data

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Frequently anticipated questions:

What does this data set describe?

Title: Aerorad data
Abstract:
Includes three raster files with data for thorium, uranium, and thorium/potassium ratios from aerial gamma-ray surveys in Alaska. Data was originally collected by contractors for the U.S. Department of Energy as part of the National Uranium Resource (NURE) program during the summer months of 1975, 1976, 1977, 1979, and 1980. For most of the surveys, the flight line spacings are 10km and the lines are oriented east-west. The nominal altitude of the aircraft above the ground was 122 meters. The U.S. Geological Survey processed these data to correct scaling differences between surveys and to convert count rate data to concentration values for potassium, uranium, and thorium. The processed data were used to calculated grids with 5km grid cells.
Supplemental_Information:
The aerial gammy-ray surveys were originally published in Duval, Joseph S., 2001, Aerial gamma-ray surveys in Alaska: U.S. Geological Survey Open-File Report 01-128. http://pubs.usgs.gov/of/2001/of01-128/
  1. How might this data set be cited?
    U.S. Geological Survey, 2016, Aerorad data:.

    This is part of the following larger work.

    Susan M. Karl (ed.), James V. Jones, III (ed.), and Timothy S. Hayes (ed.), 2016, GIS-based identification of areas that have resource potential for critical minerals in six selected groups of deposit types in Alaska: U.S. Geological Survey Open-File Report 2016-1191.

    Online Links:

    Other_Citation_Details:
    The larger work includes data sets for mineral resource data, geochemistry (stream sediment, rock, soil, mineral, and heavy mineral concentrate), igneous rock geochemical indices, lithology, and aeroradiometric data.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -168.3
    East_Bounding_Coordinate: -129.9
    North_Bounding_Coordinate: 71.4
    South_Bounding_Coordinate: 54.6
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 1976
    Ending_Date: 1980Currentness_Reference: The aerial surveys were flown in 1976, 1977, 1979, and 1980.
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: raster 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. It contains the following raster data types:
      • Dimensions 16501 x 22401, type Grid Cell
    2. What coordinate system is used to represent geographic features?
      The map projection used is NAD_1983_Alaska_Albers.
      Projection parameters:
      Standard_Parallel: 55.0
      Standard_Parallel: 65.0
      Longitude_of_Central_Meridian: -154.0
      Latitude_of_Projection_Origin: 50.0
      False_Easting: 0.0
      False_Northing: 0.0
      Planar coordinates are encoded using row and column
      Abscissae (x-coordinates) are specified to the nearest 5
      Ordinates (y-coordinates) are specified to the nearest 5
      Planar coordinates are specified in kilometer
      The horizontal datum used is NAD83.
      The ellipsoid used is GRS_1980.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257222101.
  7. How does the data set describe geographic features?
    Entity_and_Attribute_Overview:
    Rasters thorium_grs.tif and uranium_grs.tif were converted from the grd files as published in Duval, 2001. The cell value is concentration of thorium or uranium in parts per million. Raster thorium_potassium_ratio.tif is the result of dividing the thorium raster by the potassium raster as published by Duval, 2001.
    Entity_and_Attribute_Detail_Citation: Duval, 2001 and this data set

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?
    Joseph S. Duval and Keith Labay
  3. To whom should users address questions about the data?

Why was the data set created?

Aerial gamma-ray surveys capture the radioactive signatures of bedrock and surficial materials. The surveys measured the flux of gamma rays emitted as a result of the radioactive decay of the naturally occurring radioactive elements 40K, 238U, and 232Th. In this study, the processed data is used in the analyses for REE-Th-Y-Nb, sandstone uranium, and Sn-W-Mo in specialized granite deposit models.

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: 2000 (process 1 of 2)
    The original survey data were processed to correct scaling differences between surveys and to convert count rate data to concentration values. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Joseph S. Duval
    Geophysicist
    12201 Sunrise Valley Drive Mail Stop 954
    Reston, VA
    USA

    703-648-6106 (voice)
    jduval@usgs.gov
    Data sources used in this process:
    • Duval, Joseph S., 1999, Aerial gamma-ray surveys of the conterminous United States and Alaska: U.S. Geological Survey Open-File Report 99-562.
    Date: 2014 (process 2 of 2)
    Raster file thorium_potassium_ratio.tif was created by dividing the thorium raster by the potassium raster as produced by Duval, 2001. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Keith Labay
    4210 University Drive
    Anchorage, AK
    USA

    907-786-7410 (voice)
    klabay@usgs.gov
  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?
    The concentration values are estimated to be no better than about +/- 30 percent except for areas of very low concentrations. Those areas are suspected to have water at or very near the surface and the measured concentrations do not represent the rocks or soils.
  2. How accurate are the geographic locations?
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    Approximately 80 percent of Alaska is covered by aerial survey with line spacings of 10km. Less than one percent of the land surface was measured by these surveys.
  5. How consistent are the relationships among the observations, including topology?
    Unknown

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints: None
Use_Constraints:
None. Users are advised to read the publication text and metadata to understand the appropriate use and data limitations.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey
    MS902
    Box 25286
    Denver Federal Center
    Lakewood, CO
    USA

    1-888-ASK-USGS (voice)
  2. What's the catalog number I need to order this data set? USGS Open-File-Report 2016-1191
  3. What legal disclaimers am I supposed to read?
    This publication was prepared by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, expressed or implied or assumes any legal liability or responsibility for the accuracy, product, or process disclosed in this report, or represents that its use would not infringe privately owned rights. Reference therein to any specific commercial product, process, or service by trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 15-Dec-2015
Last Reviewed: 06-Sep-2016
Metadata author:
U.S. Geological Survey
Attn: Nora Shew
4210 University Drive
Anchorage, AK
USA

907-786-7445 (voice)
nshew@usgs.gov
Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
Generated by mp version 2.9.34 on Fri Nov 4 13:20:40 2016