MAPPING ERUPTION FACIES FROM CINDER CONES AND ASSOCIATED FLOWS USING LIDAR, SW UTAH

Basaltic volcanoes are among the most common continental volcanic landforms, and because of their complex eruptive histories and processes, morphologies can range from small pyroclastic mounds to large extensive shield volcanoes. For this study, nine distinct basaltic cinder cone volcanoes in the Basin and Range- Colorado Plateau transition zone of southwestern Utah were mapped and the relationships between age, morphology, and composition were examined. Volcanoes and associated flows were mapped using hillshade maps created from 2-meter bare earth LIDAR data combined with existing geologic maps and age data published by the Utah Geologic Survey.

Our results suggest that relative age dating based on cinder cone slope is not reliable. The degree of vegetation cover was also found to have little correlation with cinder cone age. Volcanic slope and vegetation cover appear to be controlled by local microclimate and degradation forces. Flow compositions were also examined, with a pattern of increasing silica-content and alkalinity moving northward. Given the reasonably close proximity of cinder cones, it is possible that northern magmas were derived from sources with greater continental crust input, consistent with a greater abundance of quartz xenocrysts observed in lavas associated with northernmost cones. Finally, lava flow length is correlated with calculated effusion rate rather than slope or variation in basaltic silica content.