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TitleDeveloping a geographic expert system for regional mapping of volcanogenic massive sulfide (VMS) deposit potential
AuthorReddy, R K T; Bonham-Carter, G F; Galley, A G
SourceNonrenewable Resources vol. 1, no. 2, 1992 p. 112-124,
Alt SeriesGeological Survey of Canada, Contribution Series 27091
PublisherSpringer Nature
Mediapaper; on-line; digital
File formatpdf
AreaPot Lake; Ghost Lake; Chisel Lake; Lost Lake
Lat/Long WENS-100.2000 -100.1000 54.9333 54.8333
Subjectsvolcanogenic deposits; sulphides; probability distributions; mineral deposits; mineral exploration; mineral potential; greenstone belts; modelling; mapping techniques; alteration; mineral occurrences; Geographic Information System (GIS); Geographic Expert System (GES); spatial analysis
Illustrationslocation maps; schematic diagrams; geological sketch maps; tables; graphs
ProgramRusty Lake-Snow Lake Mining Camps, Canada-Manitoba Exploration Science and Technology (EXTECH I) Initiative, 1989-1994
AbstractA personal computer-based geographic information system (GIS) is used to develop a geographic expert system (GES) for mapping and evaluating volcanogenic massive sulfide (VMS) deposit potential. The GES consists of an inference network to represent expert knowledge, and a GIS to handle the spatial analysis and mapping. Evidence from input maps is propagated through the inference network, combining information by means of fuzzy logic and Bayesian updating to yield new maps showing evaluation of hypotheses. Maps of evidence and hypotheses are defined on a probability scale between 0 and 1. Evaluation of the final hypothesis results in a mineral potential map, and the various intermediate hypotheses can also be shown in map form.
The inference net, with associated parameters for weighting evidence, is based on a VMS deposit model for the Chisel Lake deposit, a producing mine in the Early Protoerzoic Snow Lake greenstone belt of northwest Manitoba. The model is applied to a small area mapped at a scale of 1:15,840. The geological map, showing lithological and alteration units, provides the basic input to the model. Spatial proximity to contacts of various kinds are particularly important. Three types of evidence are considered: stratigraphic, heat source, and alteration. The final product is a map showing the relative favorability for VMS deposits. The model is implemented as aFortran program, interfaced with the GIS. The sensitivity of the model to changes in the parameters is evaluated by comparing predicted areas of elevated potential with the spatial distribution of known VMS occurrences.