Airborne magnetic and radiometric survey, Upper Peninsula, Michigan, and parts of northern Wisconsin, 2025

This data release provides digital flight line data for a high-resolution airborne magnetic and radiometric survey over much of the Upper Peninsula of Michigan and nearby parts of northern Wisconsin. The airborne survey was funded by the Earth Mapping Resources Initiative (Earth MRI). The survey was designed by the USGS in collaboration with the Michigan Geological Survey and contracted by the USGS. The survey was designed to meet complementary needs related to geologic mapping and characterization of mineral resource potential. A total of ca. 216,000 line kilometers (km) of magnetic and radiometric data were acquired over an area totaling ca. 38,400 km^2 across two survey blocks. Data were collected from airplanes flown at a nominal terrain clearance of 100 meters (m) above topography along flight lines spaced at 150 m intervals for Block A (western block) and 400 m intervals for Block B (eastern block). The flight lines were flown N-S. Tie lines were flown E-W every 1500 m for Block A (western block) and every 4000 m for Block B (eastern block). Data were collected by Woolpert, Inc. and EON Geosciences Inc. under contract to the USGS using airplanes with magnetometers mounted in stingers and fully calibrated gamma-ray spectrometers. The survey operated out of airports in Eagle River and Land O’ Lakes, Wisconsin; and Marquette, Escanaba, Kincheloe, Houghton, and Manistique, Michigan, from June of 2025 to October of 2025. Files that are available in this publication include flight line data for the magnetic and radiometric survey, and reports 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 reports describing the survey and data reduction. Binary files in this package are readable using the free software "Geosoft Viewer"" or commercial software "Oasis montaj". One or more files contain data available in comma separated value (.csv) file format, GeoTiff raster format (.tif), and geospatial vector format (.shp). The user must have software capable of opening these files.