REFINING THE TIMING OF TETON FAULT MOTION AND UPLIFT OF THE TETON RANGE USING LOW-T THERMOCHRONOLOGY

In recently active systems low-T thermochronologic techniques can be used to contrain the growth evolution of normal fault systems. Conventionally, normal faults grow by simultaneously elongating and accumulating displacement. Such growth should lead to a predictable pattern for the variation in displacement magnitude and slip onset ages defined by thermochronologic analysis along strike. In these models, the oldest slip onset age and greatest displacement should be located near the center of the fault, whereas younger ages and steadily decreasing displacement magnitude should be observed near fault tips. In a recent study of the Teton normal fault, a structure with a historically debated slip history, Brown et al. (2017) utilized inverse thermal history models (QTQt) of apatite (U-Th)/He (AHe) ages from three subvertical transects collected from the immediate footwall in the northern (Mt. Moran), central (Grand Teton), and southern (Rendezvous Mtn.) portions of the range to suggest that the Grand Teton may not represent the center of this normal fault system. That study recognized that fault slip and subsequent uplift of the Teton range began first at Mt. Moran (~13 Ma), and became progressively younger to the south, with the Grand and Rendezvous transects yielding rapid uplift onset ages of ~10 Ma-present and 7 Ma-present respectively. If correct, these results indicate that either Mt. Moran or even potentially farther north may represent the approximate center of the Teton Fault, rather than the classic interpretation that the Grand Teton lies at the approximate fault center. Here, we test this hypothesis by presenting results for two additional subvertical AHe transects. The first of the new transects was collected about 8km north of the previously sampled Mt. Moran transect, at Eagles Rest Peak and the second transect was collected slightly further north of Rendezvous Mountain (~6km), at Static Peak. With the addition of these new transects, we hope to further constrain the uplift ages along the Teton Fault and provide a revised comprehensive interpretation on growth evolution of this crustal-scale structure.