Airborne magnetic and radiometric survey over northwest Arkansas, 2019-2020 (version 2.0, May 2026)

This data release contains digital radiometric flight line data for a high-resolution airborne magnetic and radiometric survey over an area of northwest Arkansas (version 2.0, May 2026). Data and documentation for the original version, including associated airborne magnetic data, can be found at https://doi.org/10.5066/P91O2Y8W. The airborne geophysical survey was jointly funded by the USGS National Cooperative Geologic Mapping Program and the Earth Mapping Resource Initiative and was designed to meet the complementary needs related to geologic mapping and mineral resource research. The survey covers an irregular area 225 by 110 kilometers over the transition between the Ouachita and Ozarks Plateau physiographic provinces and includes 67,614 line-kilometers of radiometric data. Data were collected from a fixed-wing aircraft flown at mean terrain clearance of 167 meters above topography along N-S flight lines spaced at 200 meter intervals. Tie lines were flown in an E-W direction every 3000 meters. Data were collected by EON Geosciences under contract with the USGS using a fixed wing aircraft with a fully calibrated gamma-ray spectrometer. The survey operated out of the Branson, Missouri, airport from October of 2019 to March of 2020. This version (2.0, May 2026) of the radiometric data has been reprocessed from the original dataset by New Resolution Geophysics (NRG) in 2024 under contract by the USGS using noise-adjusted singular value decomposition (NASVD) spectral component analysis procedure for improving the signal-to-noise ratio of the radiometric data. This website includes the reprocessed radiometric data, with and without spectra, provided in ASCII (.csv) and NetCDF (.nc) files; GeoTIFF images showing the total count (K, U, Th), percent potassium (%K), equivalent uranium (eU), equivalent thorium (eTh), and ternary (%K, eU, eTh); 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 including Geosoft databases and grids for this radiometric dataset and the report describing the survey and data reduction. These files are provided as received from the contractor. The files in this package are readable using the free software Geosoft Viewer or the commercial Oasis Montaj software.