This data release is a re-release of an airborne geophysical survey carried out for the United States Geological Survey (USGS) by Spectra Exploration Geoscience Corp., from November 2000 to February 2001. The purpose of this survey was to acquire high-resolution, high-sensitivity aeromagnetic data over an area in northeast and north-central North Dakota and assess the area for anomalies and magnetic features pertaining to the local geology. To achieve this purpose, the survey area was systematically traversed by an aircraft carrying geophysical instruments along parallel flight lines (traverses) spaced 0.25 miles (400 meters) apart in an east-west alignment. Tie lines were flown normal to the traverses spaced at 5 miles (8000 meters). The nominal flying height was a best-fit draped 500 feet (150meters) above the terrain surface. The original data released were incorrectly processed before release and the data exhibited severe "herringboning" across lines. This updated version of the data release corrects these errors.

This data release provides digital flight line data for a high-resolution airborne magnetic and radiometric survey over parts of northwestern Minnesota near the town of Mentor. The airborne survey was funded by the Earth Mapping Resources Initiative and was designed to meet complementary needs related to geologic mapping and characterization of mineral resource potential. A total of 40,139-line km of magnetic and radiometric data were acquired over an irregular-shaped area of 9140 km2. Data were collected from a fixed-wing aircraft flown at mean terrain clearance of 120 meters (m) above topography along N-S flight lines spaced at 250 m intervals. Tie lines were flown in an E-W direction every 2500 m. Data were collected by EDCON-PRJ and NV5 Geospatial, Inc. under contract with the USGS using a fixed wing aircraft with a magnetometer mounted in the tail stinger and a fully calibrated gamma-ray spectrometer. The survey operated out of the Crookston, Minnesota airport from May of 2021 to July of 2021. 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. 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.

This data release provides digital flight line data for a high-resolution airborne magnetic and radiometric survey over parts of northwestern Minnesota near the town of Mentor. The airborne survey was funded by the Earth Mapping Resources Initiative and was designed to meet complementary needs related to geologic mapping and characterization of mineral resource potential. A total of 40,139-line km of magnetic and radiometric data were acquired over an irregular-shaped area of 9140 km2. Data were collected from a fixed-wing aircraft flown at mean terrain clearance of 120 meters (m) above topography along N-S flight lines spaced at 250 m intervals. Tie lines were flown in an E-W direction every 2500 m. Data were collected by EDCON-PRJ and NV5 Geospatial, Inc. under contract with the USGS using a fixed wing aircraft with a magnetometer mounted in the tail stinger and a fully calibrated gamma-ray spectrometer. The survey operated out of the Crookston, Minnesota airport from May of 2021 to July of 2021. 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. 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.

This data release provides digital flight line data for a high-resolution airborne magnetic survey over parts of northwestern Minnesota near the town of Mentor. The airborne survey was funded by the Earth Mapping Resources Initiative and was designed to meet complementary needs related to geologic mapping and characterization of mineral resource potential. A total of 40,139-line km of magnetic data were acquired over an irregular-shaped area of 9140 km2. Data were collected from a fixed-wing aircraft flown at mean terrain clearance of 120 meters (m) above topography along N-S flight lines spaced at 250 m intervals. Tie lines were flown in an E-W direction every 2500 m. Data were collected by EDCON-PRJ and NV5 Geospatial, Inc. under contract with the USGS using a fixed wing aircraft with a magnetometer mounted in the tail stinger. The survey operated out of the Crookston, Minnesota airport from May of 2021 to July of 2021. Files that are available in this child item include flight line data for the magnetic survey and a geotiff of the gridded total-field anomalies.

This data release provides digital flight line data for a high-resolution airborne magnetic survey over parts of northwestern Minnesota near the town of Mentor. The airborne survey was funded by the Earth Mapping Resources Initiative and was designed to meet complementary needs related to geologic mapping and characterization of mineral resource potential. A total of 40,139-line km of magnetic data were acquired over an irregular-shaped area of 9140 km2. Data were collected from a fixed-wing aircraft flown at mean terrain clearance of 120 meters (m) above topography along N-S flight lines spaced at 250 m intervals. Tie lines were flown in an E-W direction every 2500 m. Data were collected by EDCON-PRJ and NV5 Geospatial, Inc. under contract with the USGS using a fixed wing aircraft with a magnetometer mounted in the tail stinger. The survey operated out of the Crookston, Minnesota airport from May of 2021 to July of 2021. Files that are available in this child item include flight line data for the magnetic survey and a geotiff of the gridded total-field anomalies.

Magnetic data collected as part of a high-resolution airborne magnetic and radiometric survey over the southwest portion of the Colorado Mineral Belt in southwestern Colorado are provided as digital flight-line and grid files. Magnetic surveys measure subtle variations in the Earth’s magnetic field and are sensitive to differences in the magnetic properties of rocks from ground level to many kilometers below. Data for this survey were acquired by NV5 Geospatial, Inc. and is sub-contractors Precision GeoSurveys, Inc. and EDCON-PRJ, Inc under contract with the USGS. The survey was flown by helicopter in September and October of 2023. Magnetic data were measured from a magnetometer mounted in a stinger extending from the nose of the aircraft. The helicopter pilots followed pre-planned flight paths in a grid-like pattern, with north-south lines spaced 200 meters apart and east-west lines spaced 1,000 meters apart. Lines were flown 100 meters above ground as much as possible to resolve details of the magnetic field. This clearance could be realized in areas of low relief but higher clearances, as much as 200-500 meters, were required over rugged terrain and populated areas for safety reasons. Areas with restricted airspace, such as Wilderness Areas, were avoided. A total of 28,472 linear kilometers of data were collected along the lines, covering a 4,719 square-kilometer irregular area. EDCON-PRJ performed extensive data processing after completion of flying and delivered the final data and report in April 2024.

Magnetic data collected as part of a high-resolution airborne magnetic and radiometric survey over the southwest portion of the Colorado Mineral Belt in southwestern Colorado are provided as digital flight-line and grid files. Magnetic surveys measure subtle variations in the Earth’s magnetic field and are sensitive to differences in the magnetic properties of rocks from ground level to many kilometers below. Data for this survey were acquired by NV5 Geospatial, Inc. and is sub-contractors Precision GeoSurveys, Inc. and EDCON-PRJ, Inc under contract with the USGS. The survey was flown by helicopter in September and October of 2023. Magnetic data were measured from a magnetometer mounted in a stinger extending from the nose of the aircraft. The helicopter pilots followed pre-planned flight paths in a grid-like pattern, with north-south lines spaced 200 meters apart and east-west lines spaced 1,000 meters apart. Lines were flown 100 meters above ground as much as possible to resolve details of the magnetic field. This clearance could be realized in areas of low relief but higher clearances, as much as 200-500 meters, were required over rugged terrain and populated areas for safety reasons. Areas with restricted airspace, such as Wilderness Areas, were avoided. A total of 28,472 linear kilometers of data were collected along the lines, covering a 4,719 square-kilometer irregular area. EDCON-PRJ performed extensive data processing after completion of flying and delivered the final data and report in April 2024.

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.

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.

This publication provides digital flight line data for a high-resolution horizontal magnetic gradient and radiometric survey over an area of southeast Missouri and western Illinois. The survey represents the first airborne geophysical survey conducted 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 Terraquest, Ltd. under contract with the USGS using a fixed wing aircraft with magnetometers mounted in the tail stinger and each wing tip pod and a fully calibrated gamma ray spectrometer. The survey operated out of the Farmington, Missouri airport from December of 2018 to May of 2019. The survey covers a 146-kilometer x 154-kilometer area centered on the town of Ironton, Missouri. Data were collected along north-south flight lines spaced 300 meters (m) apart with east-west tie lines flown every 3000 m. A mean terrain clearance of 117 m was maintained except where safety dictated a higher elevation. A total of 68,375-line kilometers (km) of data were collected. Files that are available in this publication include flight line data for the magnetic gradient survey, flight line data for the 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. The 2018-2019 survey was designed to augment and connect two previous USGS airborne geophysical surveys. Adjacent surveys include a magnetic and gravity gradiometry helicopter survey flown in 2014 (McCafferty, 2016a) centered on the Pea Ridge iron mine and a magnetic and radiometric survey flown in 2016 and centered on Ironton, Missouri (McCafferty, 2016b).