Phelps, G. A. 20220824 1 ASCII and Binary Digital Data Denver, CO U.S. Geological Survey Additional information about Originators: Phelps, G.A. https://orcid.org/0000-0003-1958-2736 https://doi.org/10.5066/P9TLBM4U This publication provides digital flight line data for a high resolution magnetic and radiometric survey over an area of central Idaho, USA. The survey includes airborne geophysical data collected as part of the U.S. Geological Survey (USGS) Earth Mapping Resource Initiative (Earth MRI) effort (Day, 2019). Earth MRI is a cooperative effort between the USGS, the Association of American State Geologists, and other federal, state, and private sector organizations to improve our knowledge of the geologic framework of the United States. Data for this survey were collected by Sander Geophysics Ltd. under contract with the USGS using a rotary wing aircraft with a magnetometer mounted in the forward stinger and a fully calibrated gamma ray spectrometer. The survey operated out of the Salmon Idaho airport from September of 2021 to October of 2021. The survey covers an approximately 65 kilometer by 90 kilometer area centered on the igneous complex underlying the Salmon Challis National Forest. Data were collected along east west flight lines spaced 200 meters apart with north south tie lines flown every 2,000 meters. A mean terrain clearance of 200 meters was maintained except where safety dictated a higher elevation. A total of 16,950 line kilometers of data were collected. Files that are available in this publication include flight line data for the magnetic survey, flight line data for the radiometric survey and a report describing the survey parameters, field operations, quality control and data reduction procedures. The magnetic and radiometric survey was flown as one component of a U.S. Geological Survey (USGS) project to improve the geologic framework for research related to mineral resource, energy resource, and geologic hazards studies in the area. Results from the survey will aid in providing insight into the magnetic and radioelement signatures of exposed and concealed geology. References cited Day, W.D., 2019, The Earth Mapping Resources Initiative (Earth MRI): Mapping the nation's critical mineral resources: U.S. Geological Survey Fact Sheet 2019-3007, https://doi.org/10.3133/fs20193007. This metadata describes the following files: USA_Idaho_Cobalt_Belt_Mag.xyz USA_Idaho_Cobalt_Belt_AMF-U11N.csv 20210912 20211031 ground condition Complete Not planned -114.3750 -113.6000 45.5000 44.6670 ISO 19115 Topic Category economy economy USGS Program Mineral Resources Program MRP Geology, Minerals, Energy, and Geophysics Science Center GMEGSC Earth Mapping Resources Initiative EarthMRI Sander Geophysics Ltd airborne geophysical survey U.S. Geological Survey USGS Association of American State Geologists AASG USGS Thesaurus magnetic field (earth) geophysics geospatial datasets aeromagnetic surveying aeroradiometric surveying potassium uranium thorium USGS Metadata Identifier USGS:62ed9ca9d34eacf539725790 USGS Geographic Names Information System (GNIS), https://geonames.usgs.gov Salmon-Challis National Forest Lemhi County Custer County Common geographic areas Idaho Idaho Cobalt Belt USA United States of America Please see 'Distribution Info' for details. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although these data have been processed successfully on a computer system at the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. The USGS or the U.S. Government shall not be held liable for improper or incorrect use of the data described and/or contained herein. Acknowledgment of the U.S. Geological Survey would be appreciated in products derived from these data. Geoffrey Phelps U.S. Geological Survey, SOUTHWEST REGION Research Geologist mailing address

Mail Stop 989, 345 Middlefield Road

Menlo Park CA 94025 US 650-329-4922 650-329-5133 gphelps@usgs.gov This survey and release of the dataset was funded by the Earth Mapping Resources Initiative (Earth MRI). Daily quality control of raw radiometric and magnetic data was performed by the contractor. Further quality control measures occurred post flight by the contractor and USGS scientist-in-charge before approval and acceptance of the final data. The data have been peer reviewed and compared with related ancillary data. Data were visually inspected for reasonableness and spatial consistency. Survey parameters were checked for significant deviations from specifications: flight line location and spacing, flight plan, tie line intersections, diurnal magnetics, and solar magnetics (k). Standard software was used to investigate these parameters. Data set is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for additional details. Field quality control and assurance procedures were undertaken by the Sander Geophysical Ltd. field crew and are described in the contractor's report included with this data release. Field quality control and assurance procedures were undertaken by the Sander Geophysical Ltd. field crew and are described in the contractor's report included with this data release. The airborne survey was flown under contract to the U.S. Geological Survey by Sander Geophysical Ltd., from September 12, 2021 to October 31, 2021. The magnetic data were acquired with a Geometrics G-822A cesium-vapour split-beam sensor. The radiometric data were acquired with an SGSPEC multi-channel gamma-ray spectrometer, with 1,024 channels, for a total volume of 33.6 liters downward-looking and 4.2 liters (C-GPTB) upward-looking crystals (for measuring effects of atmospheric radon). Data were collected along east-west flight lines spaced 200 meters (m) apart with north-south tie lines flown every 2000 m. Terrain clearance varied from less than 100 m to greater than 600 m, with a mean clearance of 200 m. Terrain clearance exceeding 200 m was necessitated to adhere to safety protocol. A total of 16,976 line-kilometers (km) of data were collected. 20191005 Preliminary magnetic and radiometric data processing was undertaken by Sander Geophysical Ltd. of Ottowa Ontario, Canada. This processing workflow is described in the contractor's report included with this data release. 20200316 Final data and contractor's report were accepted and received by USGS from Sander Geophysical Ltd. 20200320 Final data were exported to CSV-format to meet open data requirements. 20200407 Vector G-polygon 1 0.000001 0.000001 Decimal degrees WGS_1984 WGS_1984 6378206.4 294.9786982 USA_Idaho_Cobalt_Belt_Mag.csv Table containing attribute information associated with the data set. Producer Defined LINE flight line Sander Geophysical Ltd. 101.00 1460.00 Line number XXXX.YY where XXXX is line number and YY is segment number FLT flight number Sander Geophysical Ltd. 1001 1035 fiducial DIR flight line direction Sander Geophysical Ltd. E W categorical YEAR year Sander Geophysical Ltd. 2021 2021 years DOY day of year Sander Geophysical Ltd. 257 303 days FTIME fiducial seconds past midnight UTC Sander Geophysical Ltd. 48845.1 86762.5 seconds LAT latitude WGS84 Sander Geophysical Ltd. 44.66740 45.48698 degrees LONG longitude Sander Geophysical Ltd. -113.5830 -114.4139 degrees GPS_X_U11 X coordinate, NAD-83 UTM ZONE 11N Sander Geophysical Ltd. 703115.7 770845.0 meters GPS_Y_U11 Y coordinate, NAD-83 UTM ZONE 11N Sander Geophysical Ltd. 4951147 5041154 meters GPS_X_U12 X coordinate, NAD-83 UTM ZONE 12N Sander Geophysical Ltd. 231865.7 295260.3 meters GPS_Y_U12 Y coordinate, NAD-83 UTM ZONE 12N Sander Geophysical Ltd. 4949678 5041713 meters GPS_Z_N83 GPS Elevation (above NAD-83 Ellipsoid) Sander Geophysical Ltd. 1302.90 3387.66 meters MSL_Z GPS Elevation with respect to the EGM2008 Geoid (Mean Sea Level) Sander Geophysical Ltd. 1314.97 3398.77 meters RADAR radar altimeter Sander Geophysical Ltd. 33.01 891.28 meters LASER laser altimeter Sander Geophysical Ltd. 31.73 852.97 meters TER Terrain, generated from laser altimeter, with respect to the EGM2008 Geoid (Mean Sea Level) Sander Geophysical Ltd. 1011.22 3328.92 meters DIURNAL Diurnal magnetic field from reference station Sander Geophysical Ltd. -10.000 17.301 nanoteslas MAGUC Uncompensated Airborne Magnetic Field Sander Geophysical Ltd. 51384.38 54542.07 nanoteslas MAGCOMP Compensated Airborne Magnetic Field Sander Geophysical Ltd. 51374.73 54535.09 nanoteslas MAGLAG Lag Corrected Compensated Airborne Magnetic Field Sander Geophysical Ltd. 51374.76 54535.04 nanoteslas MAGDC Diurnal and Lag Corrected Airborne Magnetic Field Sander Geophysical Ltd. 51375.58 54532.76 nanoteslas MAGVVC Diurnal and Lag Corrected Airborne Magnetic field with vertical velocity adjustment Sander Geophysical Ltd. 51374.22 54532.76 nanoteslas MAGLEVCOR Tie-line Levelling Corrections to Magnetic Field Sander Geophysical Ltd. -102.137 90.395 nanoteslas MAGLEV Levelled Airborne Magnetic Field Sander Geophysical Ltd. 51373.90 54532.23 nanoteslas MAGMLEVCOR Microlevelling corrections to Magnetic Field Sander Geophysical Ltd. -0.001 3.680 nanoteslas MAGMLEV Microlevelled Airborne Magnetic Field Sander Geophysical Ltd. 51374.68 54531.22 nanoteslas IGRF IGRF correction Sander Geophysical Ltd. 52923.19 53290.00 nanoteslas IGRF_REF IGRF Reference Surface, elevation with respect to the WGS-84 ellipsoid Sander Geophysical Ltd. 1311.657 3389.655 nanoteslas AMF Anomalous Magnetic field, IGRF corrected Sander Geophysical Ltd. -1000.048 1504.950 nanoteslas USA_Idaho_Cobalt_Belt_AMF-U11N.csv comma delimited text file. Coordinate system UTM zone 11 WGS84 Producer Defined UTM11XWGS84 UTM zone 11 X coordinate Producer Defined 703120.0 770840.0 meters UTM11YWGS84 UTM zone 11 Y coordinate Producer Defined 4951120.0 5041200.0 meters AMF anomalous magnetic field Producer Defined -1638.24304 1512.95605 nanotesla Database of aeromagnetic data, and data interpolated to a regular grid, 40 m spacing, of total magnetic intensity (TMI), also referred to as anomalous magnetic field (AMF) in accompanying report by Sander Geophysics, LTD. https://www.sciencebase.gov/catalog/item/ ScienceBase U.S. Geological Survey mailing and physical

Denver Federal Center, Building 810, Mail Stop 302

Denver CO 80225 United States 1-888-275-8747 sciencebase@usgs.gov 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 (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. USA_Idaho-Cobalt-Belt-Airborne-Survey-2021_MagneticData.csv 1 Table containing attribute information associated with the data set not compressed 4240 https://doi.org/10.5066/P9TLBM4U none 20220824 Geoffrey Phelps U.S. Geological Survey, SOUTHWEST REGION Research Geologist mailing address

Mail Stop 989, 345 Middlefield Road

Menlo Park CA 94025 US 650-329-4922 650-329-5133 gphelps@usgs.gov FGDC Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998