Application of GOCE Satellite Gravimetric Data For Mineral Exploration

Abstract

Gravity is directly proportional to density thereby making possible the use of measurable gravity in mapping the density variations in the earth’s interior. The use of density as a means of mineral exploration is cost-effective for wider area coverage. GOCE gravity data, collected by ESA’s GOCE satellite at 255km altitude and 10km intervals leading to the acquisition of multiple gravity points over the globe made possible the application of gravimetry in mineral exploration. Gravity disturbance data sourced from BGI- was corrected with WGM2012 corrections computed using EGM2008 geoid and ETOPO1 models, with reference gravity computed using the Somigliana formula. The gravity disturbances were mapped over Zambia using Surfer and Q-GIS, with over 600 control points of known mineral occurrences plotted together with other surface features like roads, rivers, railways, etc. By relating the control points to the varying gravity disturbances using the triple integral principle, a cautious analysis led to the geological classification of the gravity disturbances which essentially involved mapping predominant mineral occurrences across different parts of Zambia.  During ground truthing, it was observed that the results within a particular area of interest on the classified map, and those obtained using four (4) different metal detectors as well as another remote sensing method tallied. The metal detectors used were the GR-100MINI, AKS, AKS plus 3D, and Garrett Ace 400, each with its own characteristics. From the map outputs, the results showed that GOCE data can be used for geological classification and delineation of terrain types. The delineation of terrain types on the classified map output matched that on existing geological maps and also offered the delineation of sub-terrain types.