Regional Geology of Eastern Labrador
Readme File for Airborne Geophysical Surveys
The airborne geophysical survey images are available as georeferenced .tif images in the Data\Geophysics folder. The regional government surveys were conducted by the Geological Survey of Canada.  The more detailed industry surveys are from assessment reports.
Both the government and the industry surveys have associated index files to provide further details about the surveys.  The index polygons are available in the Geophysics subfolders of the file geodatabase (\GDB) and shapefile (\SHP) data folders.  
(DTM=digital terrain model, Mag=magnetic; EM=electromagnetic)
Government\Mag_ResidualField:  residual magnetic intensity (800 m line spacing, 200 m grid cell size), regional aeromagnetic surveys, southeast Labrador (Geological Survey of Canada)
Industry\DTM:  “digital terrain model” or estimated ground surface elevation, usually determined by subtracting radar (or laser) altimetry from GPS elevation of the aircraft, as recorded during airborne surveys
Industry\EM\AppRes_EM:  apparent ground resistivity, as determined from frequency domain (0.5-75 kHz) EM airborne surveys (differing frequencies/EM coil configurations can yield varying results: estimated resistivities of equivalent layers having varying thicknesses)
Industry\EM\TimeDomain_EM:  results from time-domain EM airborne surveys.  Here, “Zoff” is the apparent conductivity, as determined from one of the “signal off” time Bz responses, where Bz is the vertical magnetic component of the induced EM field
Industry\EM\VLF_EM:   Very Low radio Frequency (5-30 kHz) electromagnetic responses, airborne VLF-EM surveys
Industry\Mag\Mag_1VD:  first vertical derivative of airborne magnetic field, airborne surveys
Industry\Mag\Mag_2VD:  second vertical derivative of field magnetic, airborne surveys
Industry\Mag\Mag_AnSig:  analytic signal, determined from magnetic field, airborne surveys
Industry\Mag\Mag_TotalField:  total field or residual magnetic intensity, airborne surveys
Industry\Radiometric\ExpRate:  equivalent exposure rate or total count (TC) radiation, airborne gamma-ray surveys
Industry\Radiometric\K:  equivalent potassium concentration, airborne gamma-ray surveys
Industry\Radiometric\Th:  equivalent thorium concentration, airborne gamma-ray surveys
Industry\Radiometric\ThK_Ratio:  ratio of equivalent thorium to equivalent potassium concentration, airborne gamma-ray surveys
Industry\Radiometric\U:  equivalent thorium concentration, airborne gamma-ray surveys
Industry\Radiometric\UK_Ratio:  ratio of equivalent uranium to equivalent potassium concentration, airborne gamma-ray surveys
Industry\Radiometric\UTh_Ratio:  ratio of equivalent uranium to equivalent thorium concentration, airborne gamma-ray surveys

Contact for further information on the geophysics:
GeoScienceOnline@gov.nl.ca