PRELIMINARY GIS ANALYSIS OF THE GEOMORPHOLOGY AND EXTENT OF SURFICIAL DEPOSITS OF RUBY MOUNTAIN VOLCANO, NORTHWESTERN BRITISH COLUMBIA, CANADA

Ruby Mountain volcano (Lat: 59o 42'00'' N / Long: 133o 24'00'' W), located 25 km east of the town of Atlin, northwestern British Columbia, is part of the northern Cordilleran volcanic province and is thought to have formed within the last 500 k.y. (cf. Edwards and Russell, 2000). The volcano comprises lava flows, deposits of airfall tephra, and volcanic breccia. All of the lavas have aphanitic porphyritic textures with <1 % phenocrysts of olivine and plagioclase, olivine and opaque oxides in the groundmass. Small xenoliths of feldspar + quartz are common in the samples and appear to document assimilation of crustal rocks by the lavas. Ultramafic xenoliths <1 cm in diameter were found in one location.

We are using ArcView GIS to analyze the aerial extent of volcanic units and landslide deposits at Ruby Mountain and to study the 3-dimensional geomorphology of the edifice. The summit of Ruby Mountain is a partly preserved crater, rising 695 m from the valley floor of Ruby Creek to an elevation of 1895 m. The northern and western sides of the edifice have been partly excavated by ice and rock glaciers, and have experienced minor slope failures. Deposits from a recent landslide, which dissected the eastside of the edifice, extend east from the volcano across Ruby Creek. The landslide scarp displays a cross section through the upper part of the volcanic cone, which contains exposures of lava flows interbedded with consolidated tephra. Our preliminary estimates indicate that the edifice has a maximum surface area of 2.1 km2 and a maximum volume of 0.3 km3.

Edwards, B.R. & Russell, J.K. 2000. The distribution, nature and origin of Neogene-Quaternary magmatism in the Northern Cordilleran Volcanic Province, northern Canadian Cordillera. Geological Society of America Bulletin, v. 112, no. 8, 1280-1295.