Application of geometric mean method in integrating geochemical informative layers to produce geochemical evidence map

A geochemical evidence map is one of the most important informative layers in minerals potential mapping. In this research, In order to overcome the disadvantages of discrete evidence maps, we used the continuous fuzzy method to produce geochemical evidence maps. The Varzaghan 1:100,000 sheet map that is located in arasbaran metallogenic belt and hosted the Sungun porphyry-skarn copper deposit was studied. In this study, we have used 1067 stream sediment samples as primary data that was studied by Geological Survey of Iran. At first, the catchment basins for each sample have been drawn and the signature of samples have been allocated to corresponding basins. In addition, the signature elements of porphyry copper deposits like Cu, Mo, Ag, Au, As, Pb and Zn have been used to detecting the potential mineralized areas in the region. In the interest of fuzzifying the maps of each signature elements that mentioned, Large and logistic fuzzy functions have been used. Following to fuzzifying, the geometric average method has been applied and then prediction-area plots was used to validate the results. It has been shown that fuzzification by Large function is better as it can predict the 80 percent of mineral occurrences by utilizing 20 percent of the study area