Fusso, L.A. Petersen, E.I. Emond, A.M. EON Geosciences Inc. 20250310 digital data Geophysical Report GPR 2025-4 Fairbanks, Alaska, United States Alaska Division of Geological & Geophysical Surveys Suggested Citation: Fusso, L.A., Petersen, E.I., Emond, A.M., EON Geosciences Inc., 2025, Tofty airborne magnetic and radiometric survey, Alaska: Alaska Division of Geological & Geophysical Surveys Geophysical Report 2025-4, https://doi.org/10.14509/31494 https://doi.org/10.14509/31494 Tofty airborne magnetic and radiometric survey, Alaska, Geophysical Report 2025-4, covers an area within the Tanana Quadrangle west of Fairbanks, Alaska. Magnetic and radiometric data were collected with a helicopter between August 25, 2024, and August 30, 2024, by EON Geosciences Inc. The survey contains a single block covering 298 km2. A total of 2,231.3 line-kilometers were collected. The magnetometer was installed inside the stinger attached to the helicopter nose. The airborne gamma-ray spectrometer was mounted on the interior floor of the helicopter cabin. The block was flown with a line spacing of 200 m, except for the northeastern portion of the block that was flown with a 100 m spacing. The nominal height of the survey was 134 m. Tie-lines for magnetic leveling were flown at 1,200 m spacing. The data, as well as additional metadata, are available from the DGGS website: https://doi.org/10.14509/31494 The data from the Tofty airborne magnetic and radiometric survey, Alaska, will be used for improving the understanding of the region's geology and mineral potential and to promote resource exploration. This survey is part of the continuous regional magnetic data coverage of Alaska. >databases_geosoft: Geosoft format database of final line data, other Geosoft format databases >maps_pdf_format: Printable and geographically registered maps in pdf format. Compatible with mobile device navigation and desktop mapping applications. >vector_data: Line path and survey boundary in ESRI shapefile (SHP) format 2024 ground condition In work None planned -151.343379 -150.437335 65.190823 64.995591 USGS Metadata Identifier USGS:681b78bdd4be0225d797167f ISO 19115 Topic Category geoscientificInformation Alaska Division of Geological & Geophysical Surveys Aeromagnetic Aeromagnetic Data Aeromagnetic Map Aeromagnetic Survey Airborne Geophysical Survey Analytic Signal DGGS Exploration Geologic Geology Geophysical Map Geophysical Survey Geophysics Geophysics Search Tag Gridded Data Line Data Magnetic Data Magnetic Survey Magnetics Radiometrics Remote Sensing Alaska Division of Geological & Geophysical Surveys American Creek Baker Creek Blowback Creek Cache Creek Camp Creek Colorado Creek Cooney Creek Deep Creek Deep Creek Lakes Dome Creek Eldorado Creek Fish Lake Gold Basin Creek Killarney Creek New York Creek Quartz Creek Ready Money Creek Sullivan Creek Tamarack Creek Tofty Tonawanda Creek Utah Creek Woodchopper Creek No 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). No use constraints. We request that the suggested citation be included in any publications that reference or utilize these data. Alaska Division of Geological & Geophysical Surveys Metadata Manager Mailing and Physical

3354 College Road

Fairbanks AK 99709-3707 USA (907)451-5020 (907)451-5050 dggspubs@alaska.gov 8 am to 4:30 pm, Monday through Friday, except State holidays 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. This work was supported by the U.S. Geological Survey Earth MRI program grant G23AC00408; additional funding was provided by AK USA Critical Metals Inc. 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. Data originate from one company using DGGS contract specifications for all data (see accompanying project report). The originating coordinate system was retained for all publication products. The data release is a partial release of the contractor deliverable. This data set includes files that contain processed aeromagnetic measurements, radiometric measurements, magnetic measurements, altimetry measurements, and locational data for the entire survey area. The data release is a partial release of the contractor deliverable. Station coordinates were positioned using a real-time or post-processed corrected differential GPS. Data collection, processing, and delivery - The airborne geophysical data were acquired under contract with EON Geosciences Inc. Airborne geophysical data for the areas were acquired and processed by EON Geosciences Inc. The survey contains a single block covering 298 km2. A total of 2,231.3 line-kilometers were collected. The magnetometer was installed inside the stinger attached to the helicopter nose. The airborne gamma-ray spectrometer was mounted on the interior floor of the helicopter cabin. The block was flown with a line spacing of 200 m, except for the northeastern portion of the block that was flown with a 100 m spacing. The nominal height of the survey was 134 m. Tie-lines for magnetic leveling were flown at 1,200 m spacing. 2024 Data cataloged for archival and publication - Final data were published and archived by DGGS. 2024 Raster Universal Transverse Mercator 5 0.999600 -153 0 500000.000000 0 coordinate pair 0.00000001 0.00000001 Meters WGS84 WGS 84 6378137 298.257223563 databases_geosoft Geosoft format database of final line data, other Geosoft format databases EON Geosciences Inc. maps_pdf_format Printable and geographically registered maps in pdf format. Compatible with mobile device navigation and desktop mapping applications. EON Geosciences Inc. vector_data Line path and survey boundary in ESRI shapefile (SHP) format Alaska Division of Geological & Geophysical Surveys (DGGS) Alaska Division of Geological & Geophysical Surveys Metadata Manager mailing and physical

3354 College Road

Fairbanks AK 99709-3707 USA (907)451-5020 (907)451-5050 dggspubs@alaska.gov 8 am to 4:30 pm, Monday through Friday, except State holidays 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. The Alaska Division of Geological & Geophysical Surveys is the authoritative source and distributor of these data. 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 (dggspubs@alaska.gov), 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. Contact DGGS for current pricing GeoTiff, ESRI shapefile, Geosoft binary grid (GRD), Microsoft Office documents, PDF (with or without georeferencing), 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), georeferenced photos (multiple formats), digital video (multiple formats), Geosoft ASCII XYZ, Geosoft ASCII files (PLY, i0, EXP), and KMZ. 20250310 Airborne magnetic and radiometric geophysical survey data compilation https://doi.org/10.14509/31494 Free download U.S. Geological Survey USGS ScienceBase Team Mailing and Physical

Denver Federal Center, Building 810, Mail Stop 302

Denver Colorado 80225 USA 1-888-275-8747 sciencebase@usgs.gov The U.S. Geological Survey ScienceBase (a USGS Trusted Digital Repository) is an additional distributor these data. Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey, no warranty expressed or implied is made regarding the display or utility of the data for other purposes or on all computer systems, nor shall the act of distribution constitute any such warranty. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. 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 https://www.sciencebase.gov/catalog/item/681b78bdd4be0225d797167f None 20250310 Alaska Division of Geological & Geophysical Surveys Simone Montayne Metadata Manager Mailing and Physical

3354 College Road

Fairbanks AK 99709-3707 USA (907)451-5020 (907)451-5050 dggspubs@alaska.gov 8 am to 4:30 pm, Monday through Friday, except State holidays FGDC Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998