Erosion, Emergent Faulting, and
Core Complex Exhumation in the 
Sevier Hinterland, ID

Investigations in central Idaho, in collaboration with J. Schmitt MSU and MS student Latta, and BS student Harkins, have identified the most     westerly wedge-top synorogenic deposits in the Sevier hinterland. These Smiley Creek Fm. deposits were previously interpreted as extensional basin deposits but are reinterpreted as associated with fold and emergent thrust     scarps. The growth strata we mapped in the White Knob Mountains, ID record late, out-of-sequence activity in the Sevier hinterland coincident with uplift and exhumation of the adjacent Pioneer Core Complex in the Middle     Eocene. 39Ar/40Ar geochronology on associated volcanic rocks and magneto-stratigraphic study of the alluvial and fluvial deposits provides data on deformation and synorogenic sedimentation rates. The kinematic assessment was supported by analysis of mesoscopic faulting (Anastasio et al. in prep.).