Aeromagnetic and gravity surveys of the Skaergaard intrusion in East Greenland, 1971

Aeromagnetic and gravity surveys of the Skaergaard intrusion in East Greenland were carried out in July–August 1971 as part of a grant to the University of Oregon Center for Volcanology to further study the intrusion to refine the models of crystallization of the body. The total-intensity aeromagnetic survey was flown in early July 1971 at constant barometric altitude of 1.5 km (5000 ft) using a proton precession magnetometer with a nominal line spacing of 1 km. The gravity survey used 2 gravimeters in late July–August 1971 and acquired 168 stations of which 86 were at known altitudes (mainly sea level) and 82 had altitudes measured by altimetry. Finally, a ground vertical intensity magnetic traverse was completed from north to south across the intrusion together with collection of oriented hand specimens. The hand specimens were measured for remnant magnetization and density, together with density measurements of many more specimens collected by expedition geologists for other purposes. The rocks of the intrusion are strongly reversely polarized. After terrain correction and standard Bouguer gravity reduction, the gravity anomaly dataset was corrected for all rock above sea level using the density measurements of the various zones of the intrusion together with the topographic and geologic maps (variable density Bouguer density reduction). Please see the associated open-file report (Gravity and Magnetic surveys of the Skaergaard Intrusion) for a detailed, in-depth discussion about these surveys. This data release includes 24 files: 1. The Skaergaard_data_dictionary.csv file contains an explanation of the column headings in the Aeromag_points and Gravity_points .csv, .gdb, and .shp files, and the GroundProfile.csv file. 2. The Aeromag_points.csv file contains data sourced from the aeromagnetic survey, in comma delimited (.csv) format. 3. The Aeromag_points.gdb file contains data sourced from the aeromagnetic survey, in Oasis Montaj database (.gdb) format. 4. The Gravity_points.csv file contains data sourced from the gravity survey, in comma delimited (.csv) format. 5. The Gravity_points.gdb file contains data sourced from the gravity survey, in Oasis Montaj database (.gdb) format. 6. The GroundProfile.csv file contains data sourced from the ground profile stations survey, in comma delimited (.csv) format. 7. The SkMag1.gxf file is a grid representing the magnetic survey data, in grid exchange text (.gxf) format. 8. The SkMag1.tif file is a raster file representing the magnetic survey data, in georeferenced tag image file (.tif) format. 9. The SkMag1.grd file is a grid representing the magnetic survey data, in Oasis Montaj grid (.grd) format. 10. The SkGravVBGA1.gxf file is a grid representing the gravity survey data, in grid exchange text (.gxf) format. 11. The SkGravVBGA1.tif file is a grid representing the gravity survey data, in georeferenced tag image file (.tif) format. 12. The SkGravVBGA1.grd file is a grid representing the gravity survey data, in Oasis Montaj grid (.grd) format. 13. The GroundProfileStations.shp file contains the station locations from the ground profile stations survey, in Esri shapefile (.shp) format. 14. The Aeromag_points.shp file contains the data from the Aeromag_points.csv file, in Esri shapefile (.shp) format. 15. The Gravity_points.shp file contains the data from the Gravity_points.csv file, in Esri shapefile (.shp) format. 16. The Skaergaard_Intrusion_outline.shp file shows a generalized outline of the Skaergaard intrusion, in Esri shapefile (.shp) format. 17. The Figure19_contours.shp file contains lines shown in Figure 19 of the associated 'Gravity and Magnetic surveys of the Skaergaard Intrusion' open-file report, in Esri shapefile (.shp) format. 18. The Figure19_points.shp file contains points shown in Figure 19 of the associated 'Gravity and Magnetic surveys of the Skaergaard Intrusion' open-file report, in Esri shapefile (.shp) format. 19. The Figure20_contours.shp file contains lines shown in Figure 20 of the associated 'Gravity and Magnetic surveys of the Skaergaard Intrusion' open-file report, in Esri shapefile (.shp) format. 20. The Figure20_points.shp file contains points shown in Figure 20 of the associated 'Gravity and Magnetic surveys of the Skaergaard Intrusion' open-file report, in Esri shapefile (.shp) format. 21. The Figure21_contours.shp file contains lines shown in Figure 21 of the associated 'Gravity and Magnetic surveys of the Skaergaard Intrusion' open-file report, in Esri shapefile (.shp) format. 22. The Figure21_points.shp file contains points shown in Figure 21 of the associated 'Gravity and Magnetic surveys of the Skaergaard Intrusion' open-file report, in Esri shapefile (.shp) format. 23. The Figure22_contours.shp file contains lines shown in Figure 22 of the associated 'Gravity and Magnetic surveys of the Skaergaard Intrusion' open-file report, in Esri shapefile (.shp) format. 24. The Figure22_points.shp file contains points shown in Figure 22 of the associated 'Gravity and Magnetic surveys of the Skaergaard Intrusion' open-file report, in Esri shapefile (.shp) format.