The 3D Resolution Power of the Full Tensor Gravity Gradient

Abstract

Airborne gravity tensor (or gravity gradient) surveying is one of the newest techniques for geophysical exploration. The rise in the acquisition of this data type is partially due to the fact that these data provide much more complete, extensive and higher resolution information of rock density distribution than conventional land gravity data. This has positioned Airborne Gravity Gradient (AGG) surveys among the geophysical services requested by mining companies, alongside aeromagnetic and radiometric surveys. The use of these data has been primarily to support geological mapping given the limited access to commercial software for quantitative depth interpretation. In particular, there has been a scarce development of AGG data inversion software, which has limited our understanding of the significance of these data for resolving three-dimensional subsurface targets. In this work we hypothesize that AGG data can provide more detailed information of the multidirectional variations of subsurface density. To prove this hypothesis, we developed conjugate gradient AGG-data inversion software for three-dimensional targets. This software was applied to synthetic data generated by several test assemblages of three-dimensional bodies and used to perform a Singular Value Decomposition (SVD) sensitive analysis to explore the actual resolution power of the different tensor data components and whether they are indeed superior to the conventional vertical gravity.