ESTIMATING ORE MASSES IN GRAVITY PROSPECTING

Abstract

The interpretation of the results of gravitational prospecting surveys is considered, from a theoretical point of view, in terms of the magnitude of the causative mass as distinct from the conventional interpretation in terms of the mass distribution (size, shape and depth). A general proof is given, based on Gauss’ Theorem in potential theory, that the former problem is unique and the uniqueness is illustrated by an analytical example which also serves to demonstrate the well‐known lack of uniqueness of the latter problem. Practical formulae are presented for estimating the total mass directly from the gravity data and the precision of the mass estimate is considered. The method is applied to a practical gravimeter survey over a known chromite ore body and the estimated mass is found to be in excellent agreement with estimates from core drilling.