Figure 5 - Mineral prospectivity (predictive) map derived from the Random Forest model. Figure 6 - Mineral prospectivity (predictive) map derived from the Neural Network model. 2.3. MODEL ASSUMPTIONS, DATA HANDLING AND VALIDATION STRATEGY True absence of mineralization cannot be demonstrated at regional scale. Therefore, the nonmineralized class (Class 02) was defined as areas where no known porphyry–skarn occurrences are currently reported in the national geological database. This definition reflects the present state of geological knowledge rather than geological sterility. To reduce the risk of mislabeling potentially prospective but underexplored areas as negative samples, exclusion buffers were applied around known deposits prior to sampling. In addition, negative training points were spatially was balanced through controlled subsampling of negative instances. This approach allowed the models to learn discriminative geological patterns instead of simply reproducing spatial prevalence. No synthetic distributed across the study domain to avoid clustering bias and to ensure representative coverage of geological variability.
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