| Structural culminations in the North American Cordillera occur in the hanging walls of major
thrust systems where the basal décollement rapidly shallows eastward, defining the transition
from hinterland to foreland. Deformation in the hinterland and foreland is typically active under
different temperature regimes, resulting in high and low temperature deformation at the
hinterland-foreland transition. In southeastern Idaho, we document an overlap of high and low
temperature deformation in Neoproterozoic and Cambrian rocks exposed in the core of the
Cache-Pocatello culmination in the hanging wall of the Putnam thrust. We determine relative
timing and magnitude of peak temperatures during deformation, quantify relative magnitude and
type of deformation accommodated internally within the culmination, and develop a progressive
model for development of the Putnam thrust system. We conclude that pre-thrusting stratigraphic
thickness exerts first order control over mechanisms of deformation at the hinterland to foreland
transition in Cordilleran systems.
Key Words: Culmination, North American Cordillera, Décollement, Hinterland, Foreland |