Benefits of a High Performance Airborne Gravity Gradiometer for Resource Exploration

Gedex Inc. and the University of Maryland are developing a high performance airborne superconducting gravity gradiometer system (HD-AGG). Preliminary laboratory test data demonstrating the low noise floor of the instrument are presented. The benefits of a low noise floor for resource exploration are demonstrated. The single-axis prototype provides measurements of one gravity gradient tensor diagonal element combination. The complete 3-axis system will provide measurements of three gravity gradient tensor diagonal element combinations. The gravity gradiometer will be housed in a liquid helium cryostat to maintain superconducting temperatures which will in turn be placed on a six-degree-of-freedom motion isolation platform. Instrument design inherently rejects translational accelerations and the isolation system is designed to isolate the sensor from rotational and translational vibrations. Preliminary laboratory tests demonstrating the gradiometer data to have a noise PSD below 1Eo/√Hz from 0.05 to 1 Hz are promising. The target noise floor for the instrument in airborne mode is 1Eo/√Hz from 0.001 to 1 Hz. The benefits of such high accuracy, high spatial resolution data for resource exploration are demonstrated by computing the vertical gradient of the vertical gravity component response of a kimberlite model, and by adding expected noiseto the response. An airborne gravity gradiometer having the stated performance is capable of imaging deposits beyond the detection capability of and with greater resolution than current operational, non-superconducting technology.