Merged grids of residual magnetic intensity, digital terrain model, and apparent resistivity compiled from the Tanacross, Ladue, Western Fortymile, and Fortymile geophysical surveys. The grids were compiled by Benjamin Drenth (USGS). The data, as well as additional metadata, are available from the Alaska Division of Geological & Geophysical Surveys website: http://dggs.alaska.gov/pubs/id/29555

Merged grids of residual magnetic intensity and apparent resistivity compiled from the Wrangellia, Iron Creek, Southern Delta River, Valdez Creek, and Nikolai geophysical surveys.

Merged grids of residual magnetic intensity and apparent resistivity compiled from the Northeast Fairbanks, Fairbanks, Headwaters of the Little Chena, and Circle geophysical surveys.

Merged grids of residual magnetic intensity and apparent resistivity compiled from the Beaver Creek, Fox Hills, Southern Dishna River, Aniak, Sleetmute, Iditarod geophysical surveys.

Merged grids of residual magnetic intensity and apparent resistivity compiled from the East Styx, Farewell, Middle Styx, and Styx River geophysical surveys.

Merged grids of residual magnetic intensity, digital terrain model, and apparent resistivity compiled from the Black Mountain, Liscum, Goodpaster, SE extension of Salcha River - Pogo, and Salcha River Pogo geophysical surveys.

Merged grids of residual magnetic intensity, digital terrain model, and apparent resistivity compiled from the Tok, Ladue, Slate Creek - Slana River, Alaska Highway Corridor, and Fortymile geophysical surveys.

A rich legacy of geochemical data produced since the early 1960s covers the great expanse of Alaska; careful treatment of such data may provide significant and revealing geochemical maps that may be used for landscape geochemistry, mineral resource exploration, and geoenvironmental investigations over large areas. To maximize the spatial density and extent of data coverage for statewide mapping of element distributions, we compiled and integrated analyses of more than 175,000 sediment and soil samples from three major, separate sources: the U.S. Geological Survey, the National Uranium Resource Evaluation program, and the Alaska Division of Geological & Geophysical Surveys geochemical databases. Various types of heterogeneity and deficiencies in these data presented major challenges to our development of coherently integrated datasets for modeling and mapping of element distributions. Researchers from many different organizations and disparate scientific studies collected samples that were analyzed using highly variable methods throughout a time period of more than 50 years, during which many changes in analytical techniques were developed and applied. Despite these challenges, the U.S. Geological Survey has produced a new systematically integrated compilation of sediment and soil geochemical data with an average sample site density of approximately 1 locality per 10 square kilometers (km2) for the entire State of Alaska, although density varies considerably among different areas. From that compilation, we have modeled and mapped the distributions of 68 elements, thus creating an updated geochemical atlas for the State.

Airborne geophysical surveys were conducted in the eastern Adirondacks from Dec. 7, 2015 – Dec. 21, 2015, by Goldak Airborne Surveys. The area was flown along a draped surface with a nominal survey height above ground of 125 meters. The flight line spacing was 250 meters for traverse lines and 2500 meters for control lines. Here we present downloadable magnetic data from those surveys as flight line data (csv format) or Geotiff images. Line data (EAdirondacksMag.csv) are presented as comma separated values with the following definitions (see technical report for details): LINE Flight line number DATE YYYY/MM/DD TIME Time (UTM, 24-hour) hh:mm:ss LONG Longitude, WGS84 (degrees) LAT Latitude WGS84 (degrees) x_UTM18N Easting, UTM Zone 18N, WGS84 (meters) y_UTM18N Northing, UTM Zone 18N, WGS84 (meters) RALT Radar altimeter height (meters) BALT Barometric altimeter height (meters) GPSZ GPS elevation (meters) DEM Digital Elevation Model (meters) INS_AZ Aircraft azimuth (degrees clockwise from North) INS_PITCH Aircraft pitch (degrees, nose up positive) INS_ROLL Aircraft roll (degrees, left wing up positive) RAWMAG Raw, compensated total magnetic intensity (nT) LRAWMAG Raw, compensated total magnetic intensity with lag correction (nT) BASEMAG1 Base Station 1 Magnetic field (nT) BASEMAG2 Base Station 2 Magnetic field (nT) LEVMAG Leveled total magnetic intensity (nT) MLEVMAG Micro-leveled total magnetic intensity (nT) IGRF International Geomagnetic Reference Field (IGRF) (nT) RESMAG Residual Magnetic Anomaly (MLEVMAG-IGRF) (nT) Geotiff images show the residual magnetic anomaly (file EAdirondacks_MagRes.tif). Images use projected coordinates (UTM 18N, WGS84); geotiff tags are embedded. A colorbar is provided in a separate file (Magres_colorbar.jpg).