GEOLOGICAL MAPPING IN THE ARCTIC USING REMOTELY SENSED DATA: BAFFIN ISLAND, CANADA

A study of the application of remote sensing technology for geologic mapping in Arctic terrain has been initiated as part of a Central Baffin mapping project initiated by the Geological Survey of Canada. A test site in southern Baffin Island, approximately 80 km south of Iqaluit has been chosen for testing satellite, airborne and ground spectral data for characterizing different lithologic units and alteration targets. The study area has a variety of lithologies ranging from gneissic/granitoid basement rocks to rift related volcanic and sedimentary rocks to younger overlying Paleozoic sediments, and has been mapped on a regional scale (1:100 k) by the Geological Survey of Canada. Landsat 7, Radarsat and hyperspectral data are being evaluated for their use in mapping lithology.

Preliminary analysis of the Landsat data indicates that 3-4 endmembers representing supracrustal and basement rocks can be uniquely identified. Various hues on colour composite images correlate closely with mapped lithologies. Lithological information is not visually obvious on the Radarsat image although banding may reflect lithological differences due to differential erosion. As expected, the increase in spatial and spectral resolution in the hyperspectral data in combination with the continuity of the spectral range between the VNIR and SWIR portions of the spectrum provide the ability to discriminate compositional layering and lithological patterns in greater detail than the other image types. Preliminary analysis of the data and initial field work indicates that, not only can metasediments (paragneisses), meta-gabbros, carbonates, quartzites and monzo granites be identified, but also compositional layering within these lithologies can also be clearly seen. This layering reflects internal compositional differences, primarily due to differences in iron content. The compositional layering which define continuous units on the hyperspectral imagery are not present on the geology map of the area.

This paper presents preliminary results of analysis of the remotely sensed data integrated with geochemical analysis and ground spectral measurements (using an ASD ground spectrometer) of the various lithologies present in the study area.