Indicator approach to two-dimensional problems: Theory and example

A point-recoverable reserve estimation method is presented for bi-dimensional type deposits using Journel’s indicator approach. Two new density functions are defined: ore tonnage and metal weight per unit area. The results and formulae obtained apply especially to underground deposits with no clear geological limits, and where only chemical analysis can be used to draw boundaries between ore and waste, or between levels of profit. Theoretical and numerical inconsistencies arising from a classical geostatistical approach are presented for the case of a real base metal deposit. Ore reserve calculations redone using density functions provide straightforward results and solve the previous contradictions.