Airborne Imaging Scanner Survey of Northeastern Minnesota

Abstract

An airborne imaging scanner survey was flown over two areas in the Duluth Complex and one area along the Vermilion fault zone on September 12, 1988 to detect heavy metal induced stress in plants due to the presence of buried mineral deposits. The Duluth Complex flight lines covered copper-nickel and iron-titanium mineral deposits while the Vermilion fault flight line covered Archean gold mineralization sites. The 63 channel imaging scanner had a spatial resolution of about 9-10 meters and a flight path width of approximately 6.4-7.2 kilometers along three flight lines. Supervised, unsupervised, principal components and inverted principal components analysis and Chebyshev polynomial expansions were used on data collected over two test sites, i.e., the east end of the Archean flight line and the Dunka Pit area, to learn whether or not vegetative stress could be identified in areas with known metallic mineralization. Interpretation of the Dunka Pit test site was abandoned because: 1) the test site was too small; 2) much of the canopy was dead; and 3) the test site was overwhelmed by an adjacent, highly reflective mine dump. At the Archean site, ground spectroradiometer data was collected to assist with the interpretation of the imaging scanner data. The ground data indicated spectral shifts to both longer and shorter wavelengths in vegetation over mineralized compared with unmineralized sites. However, the imaging scanner data did not indicate any evidence of vegetative stress in mineralized areas. At this point, the imaging scanner survey data are useful mainly for discriminating different types of vegetation.