VERTICAL INJECTITES OF DETACHMENT CARBONATE ULTRACATACLASITE AT WHITE MOUNTAIN, HEART MOUNTAIN DETACHMENT, WYOMING

Carbonate ultracataclasite (CUC) is found as a veneer along the bedding plane portion of the Eocene Heart Mountain detachment. At White Mountain, where the CUC is thickest, we report the discovery of six CUC dikes, as much as 1 m wide, that were intruded vertically ~120 meters from the detachment into the overlying Madison and Bighorn Formations. The horizontal basal detachment and injectite CUC material is texturally, petrographically, geochemically and isotopically identical, containing sparse, sand to pebble-sized andesitic clasts, various quartz-calcite melt spherules and armoured lapilli in a matrix (95%)of fine-grained calcite. The relationship of hanging wall displacement to fault gouge generation, and the presence of vertical 120 meter fault gouge injectites, makes the low-angle Heart Mountain detachment system anomalous to all fault systems, especially as this fault system had only one episode of motion.