Gravity gradiometry for geophysical prospecting

Abstract

Gravity gradiometers have the potential to provide gravity measurements from a moving vehicle, thus allowing airborne gravity surveys. In order to achieve this potential, exacting sensitivity and bandwidth requirements must be met by the instrument and accuracy demands in navigation and terrain surveying must be satisfied. A gravity gradiometer for geophysical prospecting has been under development at the University of Western Australia for ten years. It is an advanced instrument using cryogenic technology and superconducting electronics and is the only gradiometer developed explicitly for prospecting use, although others elsewhere are being developed for geodetic and space applications. We have already demonstrated appropriate sensitivity and bandwidth in tests of a laboratory prototype and some recent results are presented here. This paper briefly compares gradiometry with gravimetry and shows that gravity gradiometers are better suited than gravimeters to the measurement scales of interest in geophysical prospecting. This is illustrated with the results of a modelling study of the Teutonic Bore orebody.