Circle Geophysical Survey

This geophysical survey is located in north-central Alaska in the Circle mining district, about 120 kilometers northeast of Fairbanks, Alaska. Frequency domain electromagnetic and magnetic data were collected with the DIGHEM system from August to September 1993. A total of 2516.7 line kilometers were collected covering 921.5 square kilometers. Line spacing was 400 meters (m). Data were collected 30 m above the ground surface from a helicopter towed sensor platform ("bird") on a 30 m long line.

Available Data Metadata Overview
File Name	Data File Format	File Size	Info
Download circle_vector_data	Vector data	149.1 M	Read me
Download circle_maps_prn_format	Plot files	27.1 M	Read me
Download circle_databases_geosoft	Linedata Geosoft format database	21.1 M	Read me
Download circle_images_registered	Image files	30.1 M	Read me
Download circle_grids_geosoft	Gridded data Geosoft format	3.0 M	Read me
Download circle_grids_ermapper	Gridded data ER Mapper	4.3 M	Read me
Download circle_kmz	Google Earth files	25.1 M	Read me
Download circle_documents	Adobe PDF files	12.4 M	Read me
Download circle_maps_pdf_format	Adobe PDF files	49.1 M	Read me
Download circle_profiles_stacked	Adobe PDF files	17.8 M	Read me
Download circle_ascii_data	ASCII tabular files	106.2 M	Read me

Publications

GPR 2019-3. Circle electromagnetic and magnetic airborne geophysical survey data compilation. Supersedes GPR 2004-5, GPR 2004-5-1A, GPR 2004-5-1B, GPR 2004-5-1C, GPR 2004-5-2A, GPR 2004-5-2B, GPR 2004-5-3A, GPR 2004-5-3B, PDF 94-10, PDF 94-11, PDF 94-12, PDF 94-13, PDF 94-14, PDF 94-15, PDF 94-33, PDF 94-36, RI 94-14, RI 94-15, RI 94-16, RI 94-17, and RI 94-2.
GPR 2004-5. Line, gridded, and vector data, and selected plot files of the airborne geophysical survey data of the Circle mining district, central Alaska.
PDF 94-33. Digital gridded data of total field magnetics and electromagnetics for entire survey of Circle mining district.
PDF 94-11. 900 Hz resistivity contours of Circle mining district.
PDF 94-12. 7200 Hz resistivity contours of Circle mining district.
PDF 94-14. Clear mylar version of RI 94-2: Total field magnetics and electromagnetic anomalies of the Circle mining district.
PDF 94-36. Final summary of 1993 airborne geophysical surveys of the Nome, Circle, Nyac, and Valdez Creek areas. The data and maps for this publication were initially released as a compilation of several distinct geophysical surveys. The maps and digital data have subsequently been divided into the original acquisition areas: Nome, GPR 2019-11; Circle, GPR 2019-3; Nyac, GPR 2019-4; and Valdez Creek, GPR 2019-5.
RI 94-2. Total field magnetics and electromagnetic anomalies of the Circle mining district.
PDF 94-15. CD-ROM digital archive files of 1993 survey data for Nome, Circle, Nyac, and Valdez Creek mining districts. The data and maps for this publication were initially released as a compilation of several distinct geophysical surveys. The maps and digital data have subsequently been divided into the original acquisition areas: Nome, GPR 2019-11; Circle, GPR 2019-3; Nyac, GPR 2019-4; and Valdez Creek, GPR 2019-5.
RI 94-14. Total field magnetics of the Circle mining district.
RI 94-15. Color shadow total field magnetics of the Circle mining district.
RI 94-16. 7200 Hz coplanar resistivity of the Circle mining district.
RI 94-17. 900 Hz coplanar resistivity of the Circle mining district.
PDF 94-10. Flight lines of Circle mining district.
PDF 94-13. Filtered total field VLF contours of Circle mining district.