Airborne magnetic and radiometric survey, Maryland, Pennsylvania, and West Virginia, 2022-2023

This data release provides digital flight-line and gridded data for a high-resolution airborne magnetic and radiometric survey over parts of Maryland, Pennsylvania, and West Virginia. The survey was acquired as part of the USGS Earth Mapping Resource Initiative (Earth MRI) to improve our understanding of the fundamental geologic framework of the region with applications to evaluating natural resources and geologic hazards. The survey traverses four of the primary physiographic provinces of the eastern U.S., the Piedmont, Blue Ridge, Valley and Ridge, and Appalachian Plateau Provinces, and is thus described as an “Appalachian Transect.” The survey area hosts multiple known and potential mineralizing systems including mafic magmatic and volcanogenic seafloor deposits, cobalt-bearing skarn deposits, metalliferous shales, and high-Al underclays. It also contains a diffuse intraplate seismic zone and areas with increased radon risk.

Data for this survey were acquired and processed by Sander Geophysics Ltd (SGL) under contract to Dewberry and the USGS. The survey was flown from August 2022 to April 2023 with a combination of fixed wing airplanes and helicopters, with helicopter coverage over areas with more mountainous topography. Pre-planned flight lines were flown in an E-W direction with 250-m line spacing; N-S tie-lines were flown with 2500-m line spacing. The nominal flight height of 120 meters (m) above ground, with areas having higher population densities flown at a nominal height of 330 m above ground for safety reasons.  A total of 212,312 linear kilometers of data were collected covering an area that is 350-km E-W and 200 km N-S at its widest dimensions. A circular region surrounding the Catoctin Mountain Park was not covered. Following acquisition, SGL also performed extensive post-processing of the data and delivered the final databases, grids, and images. Details regarding the flights and data processing are described in the contractor report provided in this release.

Raw data in a csv format and geotiff images of the data can be downloaded directly from the two corresponding Child Item links on this page. The full contractor package contains numeric grids, shape files, geotiffs, and databases can be downloaded from this landing page (“ContractorDeliverbles_AirborneMagnetic&RadiometricSurveyAppalachianTransect2023.zip). The contractor data are in both open-source ascii formats (.xyz) and as Oasis Montaj formats (.grd and .gdb), which can be read using the free Geosoft Viewer, available for download from https://www.seequent.com/products-solutions/geosoft-viewer/. Note these .grd and .gdb files are not ESRI format files. The projection for all data files is WGS84/UTM18N.