ALASKA AIRBORNE GEOPHYSICAL SURVEY PUBLIC DIGITAL DATABASES

Public-domain airborne geophysical survey data have been collected in Alaska by the State of Alaska, Division of Geological and Geophysical Surveys (DGGS) and by the U.S. Geological Survey (USGS). The DGGS acquired airborne electromagnetic magnetic, and in some surveys, radiometric data. The USGS data consist mostly of total field magnetic data. These data sets are a unique and valuable resource for geologic interpretation and geophysical methods development. A new joint effort by the USGS and the DGGS aims to add value to these data through the application of newly developed advanced inversion methods for electromagnetic data to produce resistivity depth sections along flight lines. Derivative products are new geophysical data maps, interpretative profiles and displays. The new approach will facilitate integration of the geophysical data in the interpretation and construction of geologic framework, resource evaluations and to geotechnical studies. Both the USGS and DDGS have websites to distribute digital airborne geophysical data that will be used to distribute new derivate products.

The DGGS program for data collection and distribution has released data annually beginning in 1994, more than 40 individual surveys have been released to the public. The primary focus of the DGGS program has been on timely geophysical data release with emphasis on mineral exploration targets and commonly includes follow-up detailed geologic mapping. Airborne geophysical survey data are available through the DDGS website: http://maps.dggs.alaska.gov/gp/.

The USGS has begun new data processing in four of the DGGS survey areas (Fortymile/Good Pasture/Ladue, Styx, Alaska Highway, and Nome). In addition to apparent resistivity maps provided by the original contracts, new products from the EM data include resistivity depth sections along profiles used to produce maps of resistivity depth and other derivative products. Processing of magnetic data has resulted in susceptibility depth sections as well as enhancement of near surface and deep sources that better relate the spatial correlation of the two types of data. Current and future USGS digital data will be available through the USGS Science Base data portal: https://www.sciencebase.gov.