Airborne magnetic and radiometric survey, Cuyuna Iron Range, central Minnesota, 2023-2025

This data release provides digital flight line data for a high-resolution airborne magnetic and radiometric survey over the Cuyuna Iron Range in central Minnesota. The airborne survey was funded by the Earth Mapping Resources Initiative (Earth MRI). The survey was designed by the USGS in collaboration with the Minnesota Geological Survey, the University of Minnesota Natural Resources Research Institute, and the Minnesota Department of Natural Resources, and contracted by the USGS. The survey was designed to meet complementary needs related to geologic mapping and mineral resources. A total of ca. 162,000 line km of magnetic and radiometric data were acquired over areas totaling ca. 22,050 square km. Data was collected from a fixed wing plane. The drape was at a nominal terrain clearance of 100 meters (m) above topography along N-S flight lines spaced at 150 m intervals. Tie lines were flown in an E-W direction every 1500 m. Data was not collected over a few different Tribal Lands on the eastern area of the survey, but was collected over Camp Ripley. Data was collected by NV5 Geospatial and EDCON-PRJ under contract to the USGS using aircraft with magnetometers mounted in stingers and fully calibrated gamma-ray spectrometers. The survey operated out of the Grand Rapids, Brainerd and Alexandria Airports from October 2023 to August 2025. Files that are available in this publication include flight line data for the magnetic and radiometric survey, and a report describing the survey parameters, field operations, quality control and data reduction procedures. A zip file is provided that contains the contractor's deliverable products that includes Geosoft databases and grids for the magnetic and radiometric survey and the report describing the survey and data reduction.