Introduction 1 Geologic setting 3 Introduction to geographic information systems 3 Preprocessing of data prior to analysis 5 Geochemical backgrounds and anomaly thresholds 8 Spatial models useful for resource assessment 8 Geochemical map methods 10 Interpolated surface (array) maps 11 Drainage basin maps 12 Spatial models of mineral deposits 12 Skarn deposit model 13 Epithermal deposit models 15 Quantification of spatial models 17 Discussion 18 Database requirements 18 Computing requirements 19 Output options 19 Cost effectiveness 19 Spatial maps for geochemistry 20 Suggestions for future research 20 References cited 20 PLATES [Plates are in pocket] 1. Representative geochemical and geologic maps of the Tonopah 1 °><2° quadrangle, Nevada: Map A. Regional distribution of arsenic in stream-sediment samples represented by surface interpolation. Map B. Regional distribution of arsenic in stream-sediment samples represented by sampled drainage basins. Map C. Comparison of areal extent of arsenic-antimony-molybdenum-zinc anomalies depicted by surface interpolation and drainage-basin methods. 2. Representative geochemical and geologic maps of the Tonopah 1 °X2° quadrangle, Nevada: Map A. Distribution of total concentrations of bismuth, molybdenum, lead, and tungsten after individual element values have been adjusted according to dominant drainage-basin lithologies. Map B. Areas favorable for tungsten skarn-type mineralization, on the basis of geological and geochemical criteria. Map C. Comparison of areal extent of bismuth-molybdenum-lead-tungsten anomalies depicted by surface interpolation and drainage-basin methods.