Airborne Gravity 2010 - Geoscience Australia

Airborne Gravity 2010
The inferred lake bathymetry is depicted in Figure 6. Five known disclosed kimberlites are marked with
stars. Three of these are located under lakes. Two of the three “lake kimberlites” are associated with
apparent depths greater than 20 m, and the third is associated with an apparent depth greater than
15 m. Most of the smaller lakes in the area are less than 10 m deep. These inversion results, in
combination with coincident geophysical datasets, provide a basis for ranking other apparent depth
anomalies of appropriate size and shape as possible kimberlite targets.
Figure 5. FALCON Gzz over Ekati, NWT, Canada, terrain corrected for density 2.0 g/cc. Lake
margins shown in black.
Figure 6. Apparent depth of lakes, inferred from geometry inversion of FALCON Gzz data over
Ekati, NWT, Canada. Stars mark locations of five known kimberlites.
Conclusions
The key characteristics of the gravity gradient method are the extremely small magnitude of the
gradients and the sensitivity of the method to near-surface density variations. Some of the issues
encountered when gravity gradient data are prepared for interpretation have been illustrated. These
issues are relevant whether the data are interpreted qualitatively, in terms of domains and trends, or
quantitatively, in terms of density models.
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