The use of simulated spatially distributed data in geology

In the past few years, several papers have presented methods to simulate values of a stationary random function with the same probability distribution and autocorrelation as spatially distributed data actually observed in nature. Moreover, it is possible to have the simulated values generated around existing data and the expected simularity between the two being respected. This capability has not been exploited fully yet and the purpose of this paper is to show how simulated values can help the geologist in solving practical problems. In a first step, a simulation package written at the Ecole Polytechnique of Montreal, POLYSIM2, is described. Then, several examples of application are presented. They are concerned with the estimation of the size of geochemical anomalies, the appraisal of economic ore reserves in an uranium deposit, and finally the evaluation of the fluctuations of the mill-feed grade in a porphyry copper deposit.