This submission encompasses the airborne magnetic and radiometric survey data from the northwestern Great Basin in Nevada and California, collected under the GeoDAWN initiative: Geoscience Data Acquisition for Western Nevada. Included in the dataset are all flight details, geophysical data, and metadata gathered during the surveys. The U.S. Geological Survey (USGS) and the Department of Energy (DOE) have collaborated to acquire high-resolution airborne magnetic and radiometric data, over northern and western Nevada and eastern California, to support geologic and geophysical mapping and modeling that will assist geothermal and critical mineral studies. The surveys, referred to as GeoDAWN, span areas of major resource potential associated with the Walker Lane and western Great Basin. They were conducted under the USGS's Earth Mapping Resource Initiative (EarthMRI), with support from the DOE's Geothermal Technologies Office (GTO), and involved acquisition of aeroradiometric and aeromagnetic data that provide key information on surface geology and soil composition, and subsurface structure and geology, respectively.

The U.S. Geological Survey (USGS) and the Department of Energy (DOE) have collaborated to acquire high-resolution airborne magnetic and radiometric data, over northern and western Nevada and eastern California, to support geologic and geophysical mapping and modeling that will assist geothermal and critical mineral studies. The surveys, referred to as GeoDAWN (Geoscience Data Acquisition for Western Nevada), span areas of major resource potential associated with the Walker Lane and western Great Basin. They were conducted under the USGS’s Earth Mapping Resource Initiative (EarthMRI), with support from the DOE’s Geothermal Technologies Office (GTO), and involved acquisition of aeroradiometric and aeromagnetic data that provide key information on surface geology and soil composition, and subsurface structure and geology, respectively. Coordinated with this effort was the collection of airborne lidar (light detection and ranging) data (conducted through the USGS 3DEP Program) that yield detailed surface topographic models of the terrain over a similar extent spanned by the geophysical surveys. The GeoDAWN surveys were performed by EDCON-PRJ, Inc., under contract with the USGS from November 1, 2021 to November 20, 2022, and consisted of two different, overlapping surveys with different flight specifications (Area 1 and Area 2; Figure 1). Area 1, centered over Clayton Valley in western Nevada was selected primarily with a focus on the region’s Li-clay and brine resources. It was flown with rank 1 specifications (following criteria outlined by Drenth and Grauch, 2019) that met EarthMRI survey requirements. Area 2, consisting of the remainder of the GeoDAWN extent, was selected primarily with a focus on geothermal resources. Lower resolution flight specifications designated for Area 2 (falling between rank 1 and 2) enabled data collection across a substantially larger area (spanning numerous known, prospective, and undiscovered geothermal and mineral systems) than would have been possible with rank 1 specifications. The combined GeoDAWN area (consisting of a total of 149,030 line-km spanning an area of 51,857 sq km), was divided into four separate acquisition blocks (from north to south: Winnemucca, Fallon, Hawthorne, and Tonopah; Figure 1). The Tonopah block, which includes Area 1 and the southern part of Area 2 surveys, was flow by Precision GeoSurveys Inc. (under subcontract to EDCON-PRJ, Inc.), with a Bell Jet Ranger helicopter. Area 1 was flown with a nominal flight height targeted at 100 m above terrain over low-relief areas and 150 m over mountainous areas. Flight lines were spaced 200 m apart at an azimuth of 90 degrees, and tie lines were spaced 2000 m apart at an azimuth of 180 degrees. Area 2 was flow at a nominal flight height targeted at 150 m above terrain over low-relief areas and 200 m over mountain ranges. The survey was flown with flight lines spaced 400 m apart at an azimuth of 90 degrees, and tie lines spaced 4000 m apart at an azimuth of 180 degrees. The portion of Area 2 contained within the Tonopah acquisition block was flown with the Precision GeoSurveys’ Bell Jet Ranger, while the remainder was collected by Cloudstreet Flying Service (under subcontract to EDCON-PRJ, Inc.) and flown with a Cessna 180 and Turbo 206 fixed-wing aircraft. Nominal flight heights for both surveys were based on a best fit, pre-planned, three-dimensional draped surface designed with a maximum 22-degree climb/descent angle to follow terrain as closely as possible while maintaining a safe survey. Actual flight heights were subject to aircraft climb and descent limitations. In areas of steep terrain, the aircraft may have required deviating from the planned drape surface, and therefore variable terrain clearance should be considered when modeling and interpreting these data. Magnetic data (Figure 2) were processed by EDCON-PRJ, Inc. and include corrections for diurnal variations of the Earth’s magnetic field, magnetic field of the

The U.S. Geological Survey (USGS) and the Department of Energy (DOE) have collaborated to acquire high-resolution airborne magnetic and radiometric data, over northern and western Nevada and eastern California, to support geologic and geophysical mapping and modeling that will assist geothermal and critical mineral studies. The surveys, referred to as GeoDAWN (Geoscience Data Acquisition for Western Nevada), span areas of major resource potential associated with the Walker Lane and western Great Basin. They were conducted under the USGS’s Earth Mapping Resource Initiative (EarthMRI), with support from the DOE’s Geothermal Technologies Office (GTO), and involved acquisition of aeroradiometric and aeromagnetic data that provide key information on surface geology and soil composition, and subsurface structure and geology, respectively. Coordinated with this effort was the collection of airborne lidar (light detection and ranging) data (conducted through the USGS 3DEP Program) that yield detailed surface topographic models of the terrain over a similar extent spanned by the geophysical surveys. The GeoDAWN surveys were performed by EDCON-PRJ, Inc., under contract with the USGS from November 1, 2021 to November 20, 2022, and consisted of two different, overlapping surveys with different flight specifications (Area 1 and Area 2; Figure 1). Area 1, centered over Clayton Valley in western Nevada was selected primarily with a focus on the region’s Li-clay and brine resources. It was flown with rank 1 specifications (following criteria outlined by Drenth and Grauch, 2019) that met EarthMRI survey requirements. Area 2, consisting of the remainder of the GeoDAWN extent, was selected primarily with a focus on geothermal resources. Lower resolution flight specifications designated for Area 2 (falling between rank 1 and 2) enabled data collection across a substantially larger area (spanning numerous known, prospective, and undiscovered geothermal and mineral systems) than would have been possible with rank 1 specifications. The combined GeoDAWN area (consisting of a total of 149,030 line-km spanning an area of 51,857 sq km), was divided into four separate acquisition blocks (from north to south: Winnemucca, Fallon, Hawthorne, and Tonopah; Figure 1). The Tonopah block, which includes Area 1 and the southern part of Area 2 surveys, was flow by Precision GeoSurveys Inc. (under subcontract to EDCON-PRJ, Inc.), with a Bell Jet Ranger helicopter. Area 1 was flown with a nominal flight height targeted at 100 m above terrain over low-relief areas and 150 m over mountainous areas. Flight lines were spaced 200 m apart at an azimuth of 90 degrees, and tie lines were spaced 2000 m apart at an azimuth of 180 degrees. Area 2 was flow at a nominal flight height targeted at 150 m above terrain over low-relief areas and 200 m over mountain ranges. The survey was flown with flight lines spaced 400 m apart at an azimuth of 90 degrees, and tie lines spaced 4000 m apart at an azimuth of 180 degrees. The portion of Area 2 contained within the Tonopah acquisition block was flown with the Precision GeoSurveys’ Bell Jet Ranger, while the remainder was collected by Cloudstreet Flying Service (under subcontract to EDCON-PRJ, Inc.) and flown with a Cessna 180 and Turbo 206 fixed-wing aircraft. Nominal flight heights for both surveys were based on a best fit, pre-planned, three-dimensional draped surface designed with a maximum 22-degree climb/descent angle to follow terrain as closely as possible while maintaining a safe survey. Actual flight heights were subject to aircraft climb and descent limitations. In areas of steep terrain, the aircraft may have required deviating from the planned drape surface, and therefore variable terrain clearance should be considered when modeling and interpreting these data. Magnetic data (Figure 2) were processed by EDCON-PRJ, Inc. and include corrections for diurnal variations of the Earth’s magnetic field, magnetic field of the

This data release provides digital flight-line and gridded data for a high-resolution airborne magnetic and radiometric survey over the southwestern portion of the Colorado Mineral Belt, southwestern Colorado. The Colorado Mineral Belt is a broad, northeast-southwest trending alignment of historic mining districts that have produced multiple types of commodities, including critical minerals that are vital to the Nation's security and economy. The survey was acquired as part of the UGSS Earth Mapping Resource Initiative (Earth MRI) to improve our understanding of the fundamental geologic framework underpinning the Colorado Mineral Belt. This release covers the southwestern portion of the belt (southwest block), which includes a wide swath from the Gunnison and San Juan mining districts on the northeast to the La Plata mining district on the southwest, including parts of Chaffee, Gunnison, Saguache, Hinsdale, Mineral, Ouray, San Miguel, San Juan, Dolores, Montezuma, and La Plata Counties. Previous reports have identified several critical minerals in this region, including aluminum, antimony, fluorspar, manganese, tungsten, vanadium, and zinc. 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 in September and October of 2023 using a helicopter equipped with a magnetometer mounted in a stinger extending from the nose of the aircraft and a gamma-ray spectrometer stowed onboard. 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 maximize detection of gamma-rays and 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 data release provides digital flight-line and gridded data for a high-resolution airborne magnetic and radiometric survey over the southwestern portion of the Colorado Mineral Belt, southwestern Colorado. The Colorado Mineral Belt is a broad, northeast-southwest trending alignment of historic mining districts that have produced multiple types of commodities, including critical minerals that are vital to the Nation's security and economy. The survey was acquired as part of the UGSS Earth Mapping Resource Initiative (Earth MRI) to improve our understanding of the fundamental geologic framework underpinning the Colorado Mineral Belt. This release covers the southwestern portion of the belt (southwest block), which includes a wide swath from the Gunnison and San Juan mining districts on the northeast to the La Plata mining district on the southwest, including parts of Chaffee, Gunnison, Saguache, Hinsdale, Mineral, Ouray, San Miguel, San Juan, Dolores, Montezuma, and La Plata Counties. Previous reports have identified several critical minerals in this region, including aluminum, antimony, fluorspar, manganese, tungsten, vanadium, and zinc. 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 in September and October of 2023 using a helicopter equipped with a magnetometer mounted in a stinger extending from the nose of the aircraft and a gamma-ray spectrometer stowed onboard. 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 maximize detection of gamma-rays and 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.

Aeromagnetic data were collected along flight lines by instruments in an aircraft that recorded magnetic-field values and locations. This dataset presents latitude, longitude, altitude, and magnetic-field values.

Aeromagnetic data were collected along flight lines by instruments in an aircraft that recorded magnetic-field values and locations. This dataset presents latitude, longitude, altitude, and magnetic-field values.

Aeromagnetic data were collected along flight lines by instruments in an aircraft that recorded magnetic-field values and locations. This dataset presents latitude, longitude, altitude, and magnetic-field values.

Aeromagnetic data were collected along flight lines by instruments in an aircraft that recorded magnetic-field values and locations. This dataset presents latitude, longitude, altitude, and magnetic-field values.

Airborne electromagnetic (AEM) and magnetic survey data were collected from December 2022 through March 2023 over a distance of 11,079 line kilometers in western Nevada and eastern California; central Nevada; and northern Nevada and southeastern Oregon. These data were collected in support of the U.S. Geological Survey (USGS) Earth Mapping Resources Initiative (Earth MRI), which aims to improve knowledge of the geologic framework of the United States through new geological and geophysical mapping and to identify areas that may have the potential to contain critical mineral resources. Data were acquired by XCalibur Multiphysics with the HELITEM² time-domain helicopter-borne electromagnetic system together with the CS-3 Scintrex Cesium Vapour magnetometer. The survey was acquired at a nominal flight height of 35 meters (m) above terrain and an average height of 80 - 85 meters. AEM data were processed and inverted to produce models of electrical resistivity along flight paths, with typical total depth of investigation around 400 meters. The survey was divided into three areas of interest (AOI) and used four different configurations of the HELITEM² system: - AOI1 is located in western Nevada and Eastern California and covers numerous basins surrounding Clayton Valley and Rhyolite Ridge. The following system configurations were used: -- 21 meter diameter loop with 30 Hz base frequency. Data collected with this system are noted with the tag _21m_30Hz in the netCDF. -- 35 meter diameter loop with 7.5 Hz base frequency (system 1). Data collected with this system are noted with the tag _35m_7p5Hz_sys1 in the netCDF. -- 35 meter diameter loop with 7.5 Hz base frequency (system 2). Data collected with this system are noted with the tag _35m_7p5Hz_sys2 in the netCDF. - AOI2 is located in northern Nevada and southeastern Oregon and covers the region surrounding McDermitt Caldera. One system configuration with a 21 meter diameter loop and base frequency of 15 Hz was used for data collection. - AOI3 is located in central Nevada and covers Railroad Valley and surrounding basins. One system configuration with a 21 meter diameter loop and base frequency of 15 Hz was used for data collection. This is the same configuration used in AOI2.