Airborne Gravity 2010 - Geoscience Australia

Airborne Gravity 2010
basin. Both sub-basins seem to contain fill with a thickness in excess of 6 km. Furthermore, three
localised basement highs within the basin appear to correspond with interpreted granitoid intrusions,
the largest of which separates the two sub-basins mentioned above.
Figure 6. Three dimensional depth to basement surface of the Volta Basin, Ghana; view is from
the southeast. Inset: Basement geology of the Volta Basin.
In order to better understand the 3-D distribution of the basement lithologies, a further modelling
exercise was undertaken using the GeoModeller software package from Intrepid Geophysics. The
results were very similar to those obtained previously, however, the GeoModeller software allowed
each geological unit to be rendered as a 3-D volume (Figure 7) providing a more visually realistic
interpretation.
Conclusions
Over the last six years, significant advances have been made in airborne gravity and gravity
gradiometry. Improvements in instrument control and data processing have reduced noise levels and
improved accuracy in both GT-1A gravimetry and FALCON gravity gradiometry. The bandwidth of the
FALCON gravity can be extended to very long wavelengths by conforming to regional gravity.
Parallel improvements in 3D inversions and visualisation have made it easier to relate the gravity data
to geology, clearly demonstrating the value that airborne gravity can bring to an exploration project.
New technology in the digital FALCON AGG has led to the ability to fly HeliFALCON surveys with
consequent improvements in both sensitivity and spatial resolution. Successful joint heli-borne gravity,
magnetic and electromagnetic surveys have been flown and an airborne test has demonstrated this
same capability from a fixed-wing platform. FALCON AGG surveys have been flown in helicopter,
single engine and twin-engine aircraft.
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