REMOTE MINERALOGIC AND LITHOLOGIC MAPPING OF THE ICE RIVER ALKALINE COMPLEX, BRITISH-COLUMBIA, CANADA, USING AVIRIS DATA

The Ice River Alkaline Complex is a late Paleozoic intrusion of mafic alkaline racks, syenite, and carbonatite exposed in southeastern Briti sh Columbia, Canada. The complex intrudes Cambrian and Ordovician shal es, slates, and limestones of the Chancellor and Ottertail Formations and the McKay Group. We examined the alkaline complex and adjacent cou ntry rocks using Airborne Visible-infrared imaging Spectrometer (AVIRI S) data. The data were first calibrated to relative reflectance and th en used to spectrally map mineralogies in the study area by using a li near spectral unmixing program. This technique models each pixel spect rum in an AVIRIS image as a linear combination of unique endmember spe ctra. We selected endmember spectra from well-exposed and spectrally d istinct mineralogic units, vegetation, and snow. Four of the endmember s reflect mineralogic variations within the McKay group in the study a rea, and may represent lateral and vertical variations of sedimentary or metamorphic facies. Otherwise, the resultant spatial distribution o f endmembers shows generally close agreement with the published geolog ic map, although, in several places, our image-map is more accurate th an the published map.