A 3-D GEOLOGICAL MODEL OF THE SOUTH END OF THE BEAVERHEAD MOUNTAINS, EASTERN IDAHO, BASED SOLELY ON GEOLOGICAL MAP DATA

This poster presents a three-dimensional model of the Scott Butte and Snaky Canyon 7.5-minute quadrangles that was created using EarthVision software. Creating a 3-D geological model based solely on geological map data forces a comprehensive evaluation of the map data, especially in a structurally complex area. The southern Beaverhead Mountains are a late Miocene to Recent, northwest-trending Basin and Range horst within the Cretaceous Sevier thrust belt. Both Sevier-age thrusts and related folds and Basin and Range-related normal faults are present in the modeled area. A major scissor fault displaces the Copper Mountain thrust by at least 5000 feet. Syn-thrusting folding resulted in broad areas of overturned and near-vertical strata and isoclinal folds that are technologically challenging to model. EarthVision software has the capability to model overturned and vertically repeated strata. The model reveals displacement of Sevier thrusts and folds by younger normal faults, and helps solve structural dilemmas that were unclear from mapping and cross-section construction alone, including amount of displacement on normal faults, lateral connections between overturned strata, and continuity of structures east to west across the range.