Abstract
An iterative remote predictive mapping approach was applied in regional-scale bedrock mapping of the Boothia mainland area, Nunavut, Canada. A geological interpretation of high-resolution airborne magnetic, Landsat Enhanced Thematic Mapper (ETM), and legacy field data resulted in a provisional remote predictive map (RPM) that was used to guide regional bedrock mapping in the summer of 2005. After the newly acquired field data were incorporated in the geoscience database, the provisional RPM was upgraded to 1 : 250 000 scale geological maps in a second iteration of geological interpretation. In general, the RPM was much better at predicting where major changes in lithology occurred than at predicting specific rock types. A comparative assessment of the generalized units of the RPM and geological maps at field stations yields an overall agreement of 82.3%. The number and dimensions of supracrustal belts on the RPM, however, were exaggerated and showed a relatively low agreement of 31% with geological map units at the field stations. This is explained by the confusion between supracrustal belts and metaplutonic units being both associated with high-spatial frequency linear and low-relief magnetic anomaly patterns. Field observations confirm that linear high-spatial frequency magnetic anomaly patterns in metaplutonic units are induced by metamorphic new growth of magnetite. These magnetic anomaly patterns parallel curvilinear features extracted from Landsat imagery and foliation strike measurements to the extent that regional fold structures can be reliably traced throughout the survey area. Spectral absorption features of carbonate in Landsat ETM band 7 and the overall high albedo of quartzite and marble allow differentiating Paleoproterozoic supracrustal units from their carbonate- and quartzite-barren Archean counterparts.
Published Version
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