Mapping basement relief with airborne gravity gradiometry

Abstract

Airborne measurement of gravity tensor components provides a new means of high-resolution mapping of the gravity field. The tensor components attenuate more rapidly with increase in source depth than does gravity, so these methods are best suited to the investigation of shallow sources. A primary use of gravity studies in both petroleum and mineral exploration is the mapping of basement relief. In this study gravity tensor variations have been computed over a complex model representing a horizontally and vertically faulted basement surface. Simulated measurement noise was added to the model output to create synthetic data sets. This synthetic data was then inverted to investigate the limitations of recovering basement structure from the data. The model results presented in this study show that gravity gradients over wide and extensive vertical steps in a 0.4 gm/cc interface with amplitude +/- 10% of depth can be reasonably inverted up to noise levels of approximately 10 E.u rms. Multi-profile inversions substantially outperformed single profile inversions, indicating their value in suppressing random profile to profile noise.