Project Name: Tonsina Contracting Agency: State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys (DGGS) DGGS Section: Minerals Section Program: Alaska Airborne Geophysical and Geological Mineral Inventory Program and the Alaska Strategic and Critical Minerals Assessment Capital Improvement Program Funding Source: Alaska State Legislature Contractor: CGG Land (U.S.) Inc. Survey Flown By: CGG CGG Project Number: 14030 DGGS Contract Manager: Abraham M. Emond Data Acquisition: Digitally acquired Line miles (km): 1240.76 miles (1996.76 km) Data Acquisition: Start Date (YYYY-MM-DD): 2014-07-25 End Date (YYYY-MM-DD): 2014-08-20 Platform: Helicopter Platform: Model: AS-350-B3 Squirrel Survey Altitude Model: Mean terrain clearance (height above ground) Nominal Helicopter Height: 60 meters Nominal Bird Height: 30 meters Traverse: Line Azimuth: N15 degrees W (heading of 345 degrees) Traverse: Line Spacing: 1/4 mile (402.3 m) Tie: Line Azimuth: N75 degrees E (heading of 75 degrees) Tie: Line Spacing: approximately 3 miles (approximately 4828 m) Border lines: present around all non-parallel and non-perpendicular edges Magnetics: Magnetometer: Scintrex CS3 cesium censor, mounted in bird Electromagnetics: Sensor Model: Dighem(V) Navigation System: Sensor: Global Positioning System Navigation System: Sensor: Novatel OEM5-GL2 Navigation System: Method: Post-flight differential positioning Additional equipment: Radar and laser altimeters, video camera, and 50/60 Hz monitors Operating frequencies used for the Dighem (V) system. 24-July through 17-August, 2014 (flts 3002:3039) Cx1000 1117.0 Hz coil separation = 7.96 meters Cp900 927.9 Hz coil separation = 7.98 meters Cx5500 5923 Hz coil separation = 7.92 meters Cp7200 7281 Hz coil separation = 7.98 meters Cp56k 55380 Hz coil separation = 6.31 meters Frequencies adjusted 18-August, 2014 (flts 3042:3049) Cx1000 1115.2 Hz coil separation = 7.96 meters Cp900 909.6 Hz coil separation = 7.98 meters Cx5500 5928 Hz coil separation = 7.92 meters Cp7200 7293 Hz coil separation = 7.98 meters Cp56k 55410 Hz coil separation = 6.31 meters
Emond, A.M., CGG, Burns, L.E., Graham, G.R.C., and (US), CGG Land Inc., 2014, Tonsina electromagnetic and magnetic airborne geophysical survey data compilation: Geophysical Report GPR 2015-1, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.
Planar coordinates are encoded using coordinate pair
Abscissae (x-coordinates) are specified to the nearest 0.01
Ordinates (y-coordinates) are specified to the nearest 0.01
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 for this survey was provided by the Alaska Division of Geological & Geophysical Surveys' (DGGS) Airborne Geophysical/Geological Mineral Inventory (AGGMI) and Strategic and Critical Minerals Assessment Capital Improvement programs and managed by State of Alaska, Department of Natural Resources (DNR), Division of Geological & Geophysical Surveys (DGGS). The survey data was collected and processed by CGG.
The Tonsina electromagnetic and magnetic airborne geophysical survey data compilation is a product of the Alaska Division of Geological & Geophysical Surveys' (DGGS) Airborne Geophysical/Geological Mineral Inventory (AGGMI) program and the Alaska Strategic and Critical Minerals Assessment Capital Improvement Project. The goal of the Alaska Division of Geological & Geophysical Surveys' (DGGS) Airborne Geophysical/Geological Mineral Inventory (AGGMI) program is to enhance the understanding of Alaska's mineral resources and stimulate private-sector mineral development. The program seeks to delineate 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 Alaskans; and (3) will provide economic diversification to help offset the loss of Prudhoe Bay oil revenue. Candidate lands for this program are identified on the basis of existing geologic knowledge, land ownership, and nominations from Alaska's geologic community. The AGGMI program and resulting new geologic knowledge are recognized worldwide and have encouraged millions of dollars of venture capital expenditures in the local economies of the surveyed mining districts. These venture capital expenditures have led to discovery and delineation of new mineral resources. The multi-year Strategic and Critical Minerals Assessment Capital Improvement Project (SCMA) was established to determine Alaska's geologic potential for rare-earth elements and other minerals that are essential for our modern, technology-based society. This program began in FY2012 with a data survey and compilation of existing information on rare-earth-element occurrences in Alaska, and expanded significantly in FY2013 to include additional critical minerals, re-analyses of existing samples, and obtaining new field and analytical data, including airborne geophysics.
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:
Data sources used in this process:
Electromagnetic system contract specification: 900 Hz coplanar apparent resistivity cutoff 1325 Ohm-m 1000 Hz coaxial apparent resistivity cutoff 1501 Ohm-m 5500 Hz coaxial apparent resistivity cutoff 8001 Ohm-m 7200 Hz coplanar apparent resistivity cutoff 10750 Ohm-m 56000 Hz coplanar apparent resistivity cutoff 60000 Ohm-m Frequency; Coil Orientation; Peak-to-Peak Noise Envelope (ppm) 900 Hz horizontal coplanar 10 1000 Hz vertical coaxial 10 5500 Hz vertical coaxial 10 7200 Hz horizontal coplanar 20 56,000 Hz horizontal coplanar 40 Magnetic data contract specification: The in-flight noise envelope will not exceed 0.1 nT in straight and level flight. In rugged areas, the noise level will not exceed 0.5 nT.
A Novatel OEM5-G2L Global Positioning System was used for navigation. The helicopter position was derived every 0.5 seconds using post-flight differential positioning to a relative accuracy of better than 5 m.
CHANNEL; Valid Data Points; Missing Data Points (dummy value = *) res900; 950,442; 6,944 res7200; 950,442; 6,944 res56k; 950,442; 6,944 dep900; 565,245; 392,141 dep7200; 876,697; 80,689 dep56k; 900,248; 57,138 Missing values in the calculated 'resistivity' (res56k, res7200, and res900) and 'depth' (dep56k, dep7200, and dep900) are due to calculations being meaningless, generally caused by increase in altitude. See supporting documentation for more information.
Data originate from one company using the same contract specifications for all data. The originating data were collected using the NAD27 UTM Zone 6N coordinate system. The originating coordinate system was retained for all publication products except the KMZ files, which utilize WGS84 geographic coordinates.
Are there legal restrictions on access or use of the data?
- 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).
- 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.
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.
DGGS publications are available as free online downloads or you may purchase paper hard-copies or digital files on CD/DVD or other digital storage media by mail, phone, fax, or email from the DGGS Fairbanks office. To purchase this or other printed reports and maps, contact DGGS by phone (907-451-5020), e-mail (firstname.lastname@example.org), or fax (907-451-5050). Payment accepted: Cash, check, money order, VISA, or MasterCard. Turnaround time is 1-2 weeks unless special arrangements are made and an express fee is paid. Shipping charge will be the actual cost of postage and will be added to the total amount due. Contact us for the exact shipping amount.
|Data format:||GeoTiff, ESRI shapefile, Geosoft binary grid, Microsoft Office documents, PDF, ER Mapper ERS, ASCII text files (including CSV), Geosoft ascii grid (GXF), Geosoft database, AutoCAD DXF, Geosoft PLT, Printer file type HPP, Geosoft ASCII XYZ, and KMZ|
Technical requirements for use of all of the data on this publication includes software with ability to use, import, or convert Geosoft float GRD, Geosoft binary GDB,, ESRI Shape files or Autocad DXF, Adobe Acrobat PDF, Google Earth files, and text files. Free downloadable interfaces to view or convert the gridded and shape files are available at the Geosoft Web site (<http://www.geosoft.com>; Oasis Montaj viewer). The KMZ files can be dragged and dropped into the 'My Places' folder of the free downloadable 'Google Earth' software. Freeware software 'printfile' (<http://www.lerup.com/printfile>) prints HPGL/2 files easily on compatible printers. The HPGL/2 files have brighter colors and sharper topography than the PDF maps and should be used for printing when possible. The PDF format maps are the only maps digitally viewable in this publication.