Patterns of incision and deformation on the southern flank of the Yellowstone hotspot from terraces and topography

Abstract Understanding the dynamics of greater Yellowstone region requires constraints on deformation spanning million year to decadal timescales, but intermediate-scale (Quaternary) records erosion and are lacking. The Upper Snake River drainage crosses from uplifting that encompasses Plateau into subsiding Plain provides an opportunity investigate a transect across trailing margin hotspot. Here, we present new chronostratigraphy fluvial terraces along lower Hoback Rivers measure characteristics through Alpine Canyon interpreted in context bedrock erodibility. We attempt evaluate whether incision is driven by uplift system, subsidence Plain, or individual faults river's path. our study area incising at roughly 0.3 m/k.y. (300 m/m.y.), which similar estimates drainages leading eastern system. pattern terrace incision, however, not consistent with widely hypothesized headwater hotspot instead downstream baselevel fall as well localized normal faults. Both Astoria documented active late Quaternary, offset indicates slip rate 0.25–0.5 (250–500 m/m.y.) for fault. Although tributary channel steepness corresponds strength, patterns χ divides support west. Subsidence may be source this fall, suggest closer Grand Valley fault system could more than previously thought.