geotiffs - Images on the interpretation maps and the EM anomaly map are provided as separate GeoTiff files. maps_hpgl2 - hpgl2 format (.prn) maps. See gpr2011_004_readme.pdf. maps_pdf - Adobe Acrobat (pdf) format maps. See gpr2011_004_readme.pdf. project_report_em_anomalies - Adobe Acrobat format of Fugro Airborne Surveys' project report with interpretation EM anomaly picks for the report in csv and >Geosoft ASCII XYZ formats. File 'gpr2011-4_emanom_readme.pdf' included. sm_profiles - Adobe Acrobat format of Fugro Airborne Surveys' project stacked-multi channel profile. See Project Report for more information. vectors - ESRI Shape and Autocad DXF of interpretation, EM anomalies, and various locational reference files. See gpr2011_004_readme.pdf.
Burns, L.E., Fugro Airborne Surveys Corp., and Fugro GeoServices, Inc., 2015, Iditarod survey area: Airborne magnetic and electromagnetic data in line, grid, vector, and map formats, and descriptive project report, Innoko, Iditarod, and McGrath mining districts, Iditarod and Ophir quadrangles, western Alaska: Geophysical Report GPR 2011-4, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.Online Links:
Planar coordinates are encoded using coordinate pair
Abscissae (x-coordinates) are specified to the nearest .01
Ordinates (y-coordinates) are specified to the nearest .01
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 6378206.4.
The flattening of the ellipsoid used is 1/294.9786982.
Funding was provided by the Alaska State Legislature for the DGGS Airborne Geophysical/Geological Mineral Inventory (AGGMI) program.
(907)451-5020 (voice)
dggsgis@alaska.gov
The survey was part of the Alaska Airborne Geophysical/Geological Mineral Inventory project funded by the Alaska State Legislature and managed by State of Alaska, Department of Natural Resources (DNR), Division of Geological & Geophysical Surveys (DGGS). The project seeks to catalyze private-sector mineral development investment. The project delineates mineral zones on Alaska state lands that: 1) have major economic value; 2) can be developed in the short term to provide high quality jobs for Alaska; and 3) will provide economic diversification to help offset the loss of Prudhoe Bay oil revenue.
Akima, H., 1970, A new method of interpolation and smooth curve fitting based on local procedures: Journal of the Association of Computing Machinery v. 7, no. 4, Association for Computing Machinery, New York, NY, USA.
Fraser, D.C., 1978, Resistivity mapping with an airborne multicoil electromagnetic system: Geophysics v. 43, Society of Exploration Geophysicists, Tulsa, OK, United States.
Data sources used in this process:
Burns, L.E., Fugro Airborne Surveys Corp., and Fugro GeoServices, Inc., 2011, Iditarod survey area: Magnetic and electromagnetic line, grid, and vector data and maps, Innoko, Iditarod, and McGrath mining districts, Iditarod and Ophir quadrangles, western Alaska: Geophysical Report GPR 2011-2, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.Online Links:
Survey interpretation and documentation of data acquisition and tests done during acquisition were produced by the same company (Fugro Airborne Surveys) who acquired the data. Tests completed and constraints used are documented in the project report. Ruth Pritchard, the project report author and data interpreter, has several decades of experience interpreting aeromagnetic and electromagnetic data and making EM anomaly picks.
Accuracy of the data was discussed in the metadata for the first publication of the Iditarod survey (GPR2011-2, listed in the cross references). Other information may be included in the project report, included in the current publication. The helicopter position was derived every 0.5 seconds using post-flight differential positioning to an accuracy of better than 1 m.
The laser altimeter ('ALTLAS_BIRD'), located in the bird (EM equipment and magnetometer housing), had a stated resolution of 0.10 meter. The ALTLAS_BIRD value may be unreliable over bodies of water where the laser returns are scattered.
The data are complete.
Data originate from one company using the same contract specifications for all data.
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.
(907)451-5020 (voice)
(907)451-5050 (FAX)
dggspubs@alaska.gov
GPR 2011-4
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.
Current geophysics publications are available on paper or Mylar. Please ask for the maps to be printed from HPGL/2 files to ensure the best quality image. To purchase printed reports and maps, contact DGGS by phone (907-451-5020), e-mail (dggspubs@alaska.gov), or fax (907-451-5050). Payment accepted: cash, check, money order, VISA, or MasterCard.
| Data format: | DGGS geophysics datasets are typically compilations of multiple digital data file formats. These formats may include: GeoTiff, ESRI shapefile, Geosoft binary grid (GRD), Microsoft Office documents, PDF, ER Mapper ERS, ASCII text files (including CSV), Geosoft ASCII grid (GXF), Geosoft database, AutoCAD DXF, Geosoft plot file (PLT), Printer files (HPP, PRN, or other), digital images (multiple formats), digital video (multiple formats), Geosoft ASCII XYZ, Geosoft ASCII files (PLY, i0, EXP), and KMZ |
|---|---|
| Network links: |
<http://dx.doi.org/10.14509/27081> |
Digital files on DVD are available for $10 plus shipping and are free when downloaded online.
Requisite software varies according to the file format. Possible software requirements include, but are not limited to: Geosoft Oasis montaj (full version and viewer), INTREPID geophysical software, ESRI Arc GIS products, MapInfo, Global Mapper, UltraEdit, NotePad ++, Microsoft Office or open source office software, Adobe Reader, Lerup PrintFile, Google Earth, ER Mapper
(907)451-5020 (voice)