CONSTRAINING SPATIAL AND TEMPORAL LANDSCAPE RESPONSE RATES TO TETON FAULT ACTIVITY THROUGH APATITE HELIUM THERMOCHRONOLOGY AND LIMNOGEOLOGY

Understanding how landscapes respond to changes in tectonic and climatic forcing remains as one of the largest challenges in tectonics and geomorphology. Specifically, the rates at which landscape erosion and exhumation are able to respond to transient changes in forcing (such as fault slip and subsequent tectonic uplift) remain poorly constrained. To better understand feedback relationships between tectonics, climate, and landscape response, we separate the signals that define uplift, drainage incision, and sediment flux rates at multiple timescales. The Teton Range serves as an ideal natural laboratory for filtering this complex interplay due to its comparatively small size and consistent along-strike climatic variation.

Recent apatite U-Th/He data collected along multiple subvertical transects in the Teton Range indicate that Teton fault motion first initiated near Mount Moran in the northern portion of the range, and slip rates vary along strike. As there are no stark changes in potential climatic forcing along the range, measured landscape response rates are expected to scale appropriately with the variation in fault slip rates along strike. This would indicate that for systems of this scale and tectonic regime, tectonic forcing is the primary driver of landscape evolution. This contribution will discuss along-strike variation in slip rates as well as results from new (U-Th)/He thermochronologic studies of the major incised drainages of the Teton Range. Such age results reveal the long-term (10⁶ - 10⁷ years) landscape response of the Teton Range to tectonic forcing. Additionally, we present new high resolution seismic data collected on Jackson Lake which, when tied to core, allows for measurement of the intermediate (12,000 years) and shortest-term (10² years) landscape response via sedimentation rates since the Pleistocene-Holocene transition and the 1916 impoundment of Jackson Dam, respectively. We compare these determined response rates over multiple time scales to the variable slip rates to determine how they scale, both along-strike and through time. If these measurements do not scale directly with slip rates, then it is likely that despite its consistency, climate serves as more than a second or third order control on the landscape evolution of the Teton Range.