SP 44 Chapter 16: Integration of Geoscience Data for Mapping Potassic Alteration, Swayze Greenstone Belt, Ontario, Canada
by J.R. Harris.
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This chapter is from GAC's Special Paper 44: "GIS For the Earth Sciences" editted by Dr. Jeff Harris. To purchase the entire book in hardcopy or disc formats, please see the Special Papers section of our bookstore.
ABSTRACT: The objective of this paper is to illustrate how GIS and image analysis technology, in concert with geostatistics, can be used to identify and screen potassium anomalies in a variety of geoscience datasets. These include geochemical data sampled from rock, till, soil, humus and airborne gamma ray spectrometer data. Once identified and screened, the anomalies are compared to one another as well as the location of known mineral prospects using the weights-of-evidence (WofE) modelling technique.
Gamma-ray data is moderately useful for identifying K alteration but is much more useful for identifying different granitoid rock types based on concentrations of K-feldspar and accessory minerals. A strong surficial signature is present in the gamma-ray data. The rock geochemical data, especially altered samples, can be used as a strong vector for identifying K alteration, whereas the surficial geochemical data provide weaker evidence of K alteration. The GIS is very useful for integrating the various data types into a map that shows potential areas of K alteration by using overlay (both weighted and non-weighted) techniques. The areas of intense K alteration are moderate predictors of known base-metal and gold mineralization.
Geological Association of Canada
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